Q: What is your understanding of Zechariah 8:23? Is it possible that those with an earthly hope could be a spiritual Jew one who is approved by God?

A: According to the New World Translation, Zechariah 8:23 reads: “This is what Jehovah of armies has said, ‘It will be in those days that ten men out of all the languages of the nations will take hold, yes, they will actually take hold of the skirt of a man who is a Jew, saying: “We will go with YOU people, for we have heard [that] God is with YOU people.”’”

The Watchtower (February 15, 2009) offered the following explanation:

"The Bible book of Zechariah speaks of “ten men” who approach “a man who is a Jew” and say: “We will go with you people.” (Read Zechariah 8:23.) Since “a man who is a Jew” is spoken of as “you people,” he is a composite man. In our time, he represents the remnant of spirit-anointed Christians—part of “the Israel of God.” (Gal. 6:16) The “ten men out of all the languages of the nations” represent the great crowd of other sheep. Just as the anointed Christians follow Jesus no matter where he goes, the great crowd ‘goes with,’ or accompanies, the faithful and discreet slave. Those of the great crowd should never be ashamed to identify themselves as companions of the “partakers of the heavenly calling.” (Heb. 3:1) Jesus is not ashamed to call the anointed ones “brothers.”—Heb. 2:11. —w09 2/15 p. 27 par. 13 They “Keep Following the Lamb”. (Bold added)

Before answering your question, allow me to first of all comment on one of the strangest and also most far-reaching interpretations the Society offers, because it reveals why they have come to put such great emphasis on "the remnant of spirit-anointed Christians," as they do in the above quote. The prophet Isaiah foretold the birth of a nation as "in one day," saying: “Who has heard of a thing like this? Who has seen things like these? Will a land be brought forth with labor pains in one day? Or will a nation be born at one time? For Zion has come into labor pains as well as given birth to her sons.” (Isaiah 66:8)

The Watchtower Society has consistently applied this prophecy of Isaiah to themselves, that is, to the release from a federal penitentiary in 1919 of Judge Rutherford and his seven associates (after eight months of imprisonment). They claim it was at this time that the nation was born as in one day. The Watchtower of July 1, 1982 explained it this way:

   “Before she [that is, another Jerusalem] began to come into labor pains she gave birth. Before birth pangs could come to her, she even gave deliverance to a male child. Who has heard of a thing like this? Who has seen things like these? Will a land be brought forth with labor pains in one day? Or will a nation be born at one time? For Zion has come into labor pains as well as given birth to her sons.”—Isaiah 66:7,8. 

   "Is there a modern counterpart of the “birth” of the restored Israelites as a “nation” in 537 BCE? Yes, for in the year following the first world war of 1914-1918 a spiritual “nation” was born, under the Greater Cyrus, the enthroned King Jesus Christ! How so? Well, during the war the headquarters of the Watch Tower Bible and Tract Society, the publication agency of the International Bible Students, had been dismantled at Brooklyn, New York, and moved back to smaller quarters in Pittsburgh, Pennsylvania. Its latest pieces of literature had been banned in Canada and the United States of America, and the Society’s president, its secretary-treasurer, and six other members of the headquarters’ staff of workers had been sentenced in 1918 to long terms of imprisonment. The intent of the enemies behind all of this was like that expressed in Psalm 83:4: “Let us efface them from being a nation, that the name of Israel may be remembered no more.” But in the spring of 1919, to the shocking surprise of Christendom, there came release! That same year the persecuted International Bible Students held their first postwar convention in Cedar Point, Ohio. To the conventioners the publication of a new magazine, in addition to the Watch Tower magazine, was announced, namely, The Golden Age (now called Awake!).
   "Thus, five years after the end of the “times of the Gentiles” in 1914, and the establishment of God’s kingdom in the hands of the Greater Cyrus, Jesus Christ, a new “nation” came into existence, a spiritual “nation.” The members of this new “nation” were to serve as ambassadors of God’s kingdom newly born in the heavens and as witnesses bearing his name. He has put the “nation” in its rightful “land,” its earthly realm of activity, its symbolic “land,” now that the Gentile Times for trampling his visible organization underfoot have ended.—Lu 21:24, AV. 
w82 7/1 p. 16, 18; par. 14, 20-21 Birth of the Royal Nation on a Newborn Land. (Bold mine)

Do they really believe that this event in the Society's history, the release of the Society's president with his fellow associates, was of greater significance and importance than the day of Pentecost, at which time the prophecy of Isaiah was fulfilled and the new nation, the Christian congregation, was "born in one day" with the outpouring of the holy spirit, and the inauguration of the new covenant? Their arrogance knows no bounds, for they have continued to apply to themselves and to the developments within their secular organization many other prophecies. (Acts 20:28-30; 1 Peter 5:1-4) They have failed to differentiate between the common and the holy things, not a trivial matter in God’s eyes. (Ezek. 22:26, 28) See “Born Again—What Did Jesus Mean?”

You may already have noticed that the expression “spiritual” Israel, or “spiritual” nation, which they apply to themselves, does not appear anywhere in the Bible. This is more than merely a
quibbling over semantics, for introducing expressions and terms that are not found in the Bible can and will often lead to defining and inventing teachings that are not taught in the Scriptures, thus resulting in introducing doctrines by which we make God’s word invalid. (1 Cor. 4:6) There is a big difference between what the Bible says about the “Israel of God” and the “spiritual” Israel of the Society, where they have come up with the non-scriptural teaching that “spiritual” Israel (according to them the 144,000) actually replaced natural Israel (the Jews), as if there would have been no “Israel of God” if natural Israel had remained faithful and accepted the Messiah. (Exodus 19:5-6; Gal. 6:16; 1 Peter 2:5-6, 9) See "Did 'Spiritual Israel" Replace Natural Israel?"

Their “spiritual” Israel, or "spiritual" nation doctrine has resulted in confusion on many topics. I suppose this falls within what Paul foretold that “God lets an operation of error go to them, that they may get to believing the lie, in order that they all may be judged because they did not believe the truth.” (2 Thess. 2:11-12)

Zechariah 8:23 is one such misinterpreted prophetic scripture, which they have applied to themselves. They effectively use this prophecy to reinforce their claim that the
“ten men out of all the languages of the nations, which represent the great crowd of other sheep," must submissively accompany them as "the faithful and discreet slave," just as they follow Jesus, on account of their special relationship with God. Yes, as they say, "those of the great crowd should never be ashamed to identify themselves as companions of the 'partakers of the heavenly calling.'” Compare that to what Jesus himself said, namely that he is our one and only Leader; and rather than the "great crowd" following the 144,000, it is the 144,000 as the bride of Christ, who "keep following the Lamb no matter where he goes." (Matt. 23:10; Rev. 14:1, 4)

What is Zechariah in his prophecy talking about? The same thing that other prophets were inspired to make mention of, namely, that people of the nations would turn to God in connection with, no, not any anointed “spiritual” Jew, but rather because of the Messiah, who would be “a light to the nations.” (Isaiah 42:6; 49:6; Zech. 2:10-11; 9:9-10)

These “ten men out of all languages of the nations” who “take hold of a man who is a Jew” on account of God being with them, are the same ones Jesus pointed to when he said: “I have other sheep, which are not of this fold; those also I must bring in, and they will listen to my voice, and they will become one flock, one shepherd.” (John 10:16) Jesus was referring to the many prophecies, including Zechariah’s, which foretold that people of the nations—the “other sheep”—would come to worship Jehovah in association with the Jews on account of the Messiah, for they too were to benefit from the ransom. These people of the nations would eventually outnumber Christ's Jewish disciples [figuratively 10 to 1], belonging to the one flock, under one shepherd, namely, Christ Jesus whom they follow. (Acts 13:45-48; 28:24-28; Zech. 8:3, 20-22) See "John 10:16—Who Are the 'Other Sheep'?"

When the apostles and older men in Jerusalem met together to discuss whether Gentile believers who turned to God needed to be circumcised, James explained that the prophets had foretold that God would turn “his attention to the nations to take out of them a people for his name... [Jews] (the booth of David) together with people of all the nations, people who are called by my name, says Jehovah, who is doing these things, known from of old.” (Acts 15:14-18) The countless prophecies throughout the Hebrew Scriptures foretold that people of the nations would turn to God and join the Jews in worshiping him. There would no longer be any distinction between a Jew and a Gentile. (Rom. 2:28-29; Eph. 2:11-18)

The prophecy of Zechariah, and the many other associated prophecies have had their fulfillment starting in the first century. Bringing the Watchtower Society's “spiritual Israel" into the picture beclouds the basic and simple truth, which may cause us to follow the wrong leader.