I doubt either of them would be seriously affected. Clinton because he is mostly irrelevant in politics these days, so not much of an effort will likely focus on him. Trump because most people seem to have made up his mind about him, and most of his voters will likely stick with him over an alternative, due to policy rather than personal character considerations.
It should go without saying, but a lot of people on the right seem to have forgotten (deliberately) that their chief beef with Clinton was regarding his personal character. The GOP field for the 2000 election was basically "who can wipe the stain of infidelity and impropriety from the White House and restore the dignity of the Presidency?" The party rebranded themselves as the "family values" party in large part to set them apart from the cad who had cheated on his wife. Perish the thought. And of course the impeachment came from a lie Clinton told during a case of sexual harassment. It's almost easy to forget that the investigation which kicked it all off was into a shady real estate deal.
The Democrats self-corrected. Remember John Edwards? Cheated on his wife. Political career ended. Al Franken was caught not actually touching a woman's breasts. Political career ended.
The Republicans did a 180, throwing their full weight behind a man who cheated on his first wife with his second, his second with his third, his third with a porn star (that he paid hush money to) and by the way he made his fortune in real estate deals that make Whitewater look amateurish by comparison. The fact that Trump is friends with Epstein will not hurt him with either his supporters or his party, because they've abandoned all pretense of being the "family values" standard-bearers. If it turns out he actually assaulted a young girl or two, I have serious doubts that they'll abandon him.