Though John's authorship is not explicitly stated anywhere in the Gospel of John, the text itself points to his authorship.
The latest possible date for the writing of John's Gospel is between A.D. 110 and 120 because there is an early papyrus fragment of John (P52) dated to this period. Another papyrus fragment of an unknown Gospel known as Egerton Papyrus 2, which was largely based on John's Gospel, is dated around A.D. 130-150.
These copies give evidence of the existence of John's Gospel in at least the beginning of the second century, if not earlier. The earliest possible date for Johns Gospel is probably the late A.D. 60s. Most biblical archeologists assign a date of A.D. 80 to A.D. 90 because of John 21:23, which probably was penned while was near the end of his life.
And, it's important to note that there are more extant early manuscripts for the Gospel of John than for any other book of the New Testament.
I can name fourteen manuscripts dating from the second and third centuries. Their accuracy is confirmed by manuscripts from the fourth and fifth centuries.
That's a vague generalization that implies unanimity among the experts for a late date.
Not all "biblical scholars" would agree with statement.
Over the weekend, I saw an expert quoted to say that the Apostle John died around the year 100 AD.
The Book of Revelation is a unique Book and widely accepted as being written by the Apostle John.
Revelation bears internal witness that John was the author.
I John, who also am your brother and companion in tribulation and in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos for the Word of God and for the testimony of Jesus Christ. (Revelation 1:9)
Christian people suffered tribulation and persecution in the first century. They knew whereof they believed.