You know, if Trump were to say publicly at a press conference or interview that the Access Hollywood tape was fake, that might be the “Winston Smith” moment for a lot of Republicans who still support him. They saw the tape, the very idea that it’s fake probably never occurred to them, I’m sure they made excuses (“idle locker room talk”) for it when it came out, and Trump himself apologized for it. . . so for him to say publicly that it’s fake would portray Trump to them exactly as the rest of us see him-- delusional and childish.
Of course, a lot of conservatives would still immediately chime in “oh yeah, totally fake”, but not all. Probably a lot would admit Trump was a dolt, and still not care, as long as he’s not a Democrat.