You guys really underestimate the cultish devotion of Trump supporters. Even if she proves it's his DNA, they'll say it's still fake, or she's lying and she consented, or she deserved it, or some other gross shit.
The only thing that might make them turn is if he admits he's been a liberal Democrat this whole time, and he just faked being conservative because it was much easier to grift a bunch of RWNJ rubes.