I’m guessing it won’t have much effect one way or the other on Republican voters, who weren’t paying attention to the trial, as far as I can tell. Most Republicans — at least those not already opposed to Trump — will also likely dismiss it as part of the ongoing, politically motivated legal assault against the former president.
It will definitely add to his baggage in a general election if he’s the nominee, though.
So far, this year has been a boon to Trump and to Democrats who want him to be as weak as possible running against Biden. The verdict doesn’t change that.