Once you start to look at the gospels one by one, you realize that followers of Jesus were trying to understand what had happened after he was arrested and killed. They knew Judas had handed him over to the people who arrested him.
Startling as the Gospel of Judas sounds, it amplifies hints we have long read in the Gospels of Mark and John that Jesus knew and even instigated the events of his passion, seeing them as part of a divine plan.
There is no evidence that the author of the Book of Revelation, John of Patmos, read anything that we think of as a New Testament book. I don't see any evidence that he knew what was in the Gospels, or the letters of Paul, which I don't think he would have liked at all.