This sounded to me like another “Jesus boat.”
In 1986, during a severe drought, the Sea of Gallilee began to dry up, and in the mud someone discovered an old boat. When it was dug up, it was dated it to “about 2,000 years ago.” Therefore it was proclaimed that Jesus has probably used it, simply because of the approximate age, and the fact that He is reported to have been in boats in that area.
In the current case we have a cave that was, according to other reports, created around 800 to 500 BC, and it’s two and a half miles from where he lived. Yeah, he might have gone into the cave, but how do we know?
Byzantine-era carvings link the cave to John, although one needs an active imagination even for that. (Does the man in the illustration look like John to you?) But if they thought it was his, why didn’t they build a church around it, as they did with every other site thought to have a connection to Our Lord?
Christian tourism is a big business in Israel, so to a large segment of the population, the proof doesn’t have to be absolute. As long as Christians come to see it, that’s proof enough.