Inspired by another thread on here, I just researched the following topic and was was suprised at what I found.
Splash
MATTHEW 24:14 HAS BEEN FULFILLED?
YES - w51 10/1 p. 601 par. 7 Laying the Stone in Completion
The Gentile times ended in 1914 and the prophecies were fulfilled exactly as foretold at Matthew 24 and Luke 21, but have not been heeded by these millions.
NO - w55 10/15 p. 621 par. 1 The Triumphant Message of "The Kingdom"
Today, in this year 1955, the temple of Jerusalem is no more, as he foretold that it would not be, but his prophecy concerning "this good news of the kingdom" is being fulfilled.
YES - ws chap. 7 p. 61 par. 9 Settling Accounts Over the Use of Christ’s Funds
To mark his return, two wars of world proportions, accompanied now by many other wars of lesser proportions, have bloodied our earth. As predicted, these have been accompanied by famines, pestilences, and earthquakes, and by the increasing of lawlessness and the preaching of "this good news of the kingdom" in all the inhabited earth. This has fulfilled the details of what Jesus said would be "the sign of [his] presence and of the conclusion of the system of things."—Matthew 24:3-15.
IT APPLIES TO THE 1ST CENTURY - w92 6/15 p. 14 par. 14 Serving as Fishers of Men
For the needs of the first-century Christians, Jesus’ prophecy at Matthew 24:14 was fulfilled before Jerusalem was destroyed in 70 C.E.
YES - w92 5/1 p. 22 par. 19 Keep Awake in "the Time of the End"
As we look back over three quarters of a century, we can see how one prophecy after another has been fulfilled—the restoration of true worship; the deliverance of the anointed remnant, along with their companions, into a spiritual paradise; the preaching of the good news of the Kingdom on a global scale; the appearance of the great crowd. (Isaiah 2:2, 3; chapter 35; Zechariah 8:23; Matthew 24:14; Revelation 7:9)
NO - w93 5/1 p. 12 par. 7 Shedding Light on Christ’s Presence
(Matthew 24:7-14) Each Yearbook of Jehovah’s Witnesses adds to the evidence that these aspects of the sign are being fulfilled.
YES - w95 9/1 pp. 17-18 par. 17 Christian Witnesses for Divine Sovereignty
Jesus said: “This good news of the kingdom will be preached in all the inhabited earth for a witness to all the nations; and then the end will come.” (Matthew 24:14; Mark 13:10) Has this prophecy been fulfilled? Indeed, it has.
NO - w97 8/15 p. 14 par. 11 Living for Today or for an Eternal Future?
There is also Jesus’ prediction that "this good news of the kingdom will be preached in all the inhabited earth for a witness to all the nations; and then the end will come." (Matthew 24:14) Today, Jehovah’s Witnesses carry out their work in 233 lands, island groups, and territories. True, untouched territories still exist, and perhaps in Jehovah’s due time, a door of opportunity will open.