I'm unconvinced by Gentry's speculation about the testimony of Irenaeus.
Yes, grammatically it is possible that Irenaeus said John (he) had been seen recently, but it doesn't realistically fit the context. The context is the name of the antichrist which would have been revealed if necessary in the Revelation itself (it).
We will not, however, incur the risk of pronouncing positively as to the name of Antichrist; for if it were necessary that his name should be distinctly revealed in this present time, it would have been announced by him who beheld the apocalyptic vision. For he/it was seen no very long time since, but almost in our day, towards the end of Domitian's reign.