According to the Jehovah's Witness book called Insight Vol. 1:
"Authenticity. Some critics question the authenticity of Daniel, assuming the position taken by a third-century heathen philosopher and enemy of Christianity, Porphyry, who contended that the book of Daniel was forged by a Palestinian Jew of the time of Antiochus Epiphanes. This forger, he theorized, took past events and made them appear to be prophecies. The genuineness of the book of Daniel was not seriously questioned, however, from that day until the early part of the 18th century. Jesus Christ's own acceptance of Daniel's prophecy is an even more significant evidence of its authenticity.-Mt 24:15; Da 11:31.
Historical. Several manuscripts of parts of the book of Daniel were found in the Dead Sea Caves . The earliest manuscript dates from the first half of the first century B.C.E.; the book of Daniel was an accepted part of the Scriptures in that time and was so well known to the Jews that many copies had already been made of it. That it was recognized as a canonical book of that time is supported by the writer of the Apocryphal, but historical, book of First Maccabees (2:59, 60), who made reference to Daniel's deliverance from the den of lions, and that of the three Hebrews from the fiery furnace.
We have also the testimony of the Jewish historian Josephus, who states that the prophecies of Daniel were shown to Alexander the Great when he entered Jerusalem. This occurred in about 332 B.C.E., more than 150 years before the Maccabean period. Josephus says of the event: "When the book of Daniel was shown to him, in which he had declared that one of the Greeks would destroy the empire of the Persians, he believed himself to be the one indicated." (Jewish Antiquities, XI, 337 [viii, 5]) History also recounts that Alexander bestowed great favors on the Jews, and this is believed to have been because of what Daniel said about him in prophecy."
My thoughts: If the Jehovah's Witnesses accept the Book of Daniel as authentic based on "proof" from Jesus (Mt 24:15;Da 11:31), Dead Sea Scrolls, and Jewish Antiquities then why is the Book of Enoch which can be historically proven in the same way not accepted within their Canon? The Book of Enoch: 1) Dead Sea Scrolls, 2) mentioned in the inspired Book of Jude, 3) Tertullian (160-230 C.E) even called the Book of Enoch "Holy Scripture", 4) Josephus took his information from a source such as 1Enoch 6-11 "two stelae" and the list goes on.