Since Gentry's material is freely available online, I prefer not to be a conduit and possibly muck up his excellent presentation. IOW, don't take my word on it, or anyone else's for that matter.
At this point the only evidence we have on whether or not Revelation was written before AD 96 is your word. We do not have any extrinsic evidence. And apparently neither does Gentry.
Now if you can point us to the evidence that Gentry relies upon, that would be helpful. Otherwise will you be honest enough to admit that you simply don't have any such evidence?