I answered "no", even though, as a rock-solid Conservative, I voted for Trump, twice. If he is in prison (your OP's assumption), then he must have committed, and been convicted of, crimes. Thus, as a convicted criminal, he would not be someone that I could want to have as president. Pretty simple stuff. I won't go down into the 'rabbit hole' of 'woulda, coulda, shoulda', because your OP's proposition is quite narrow. Now, so is my response.
I would not consider any conviction secured by the present regime to be fair or legitimate so yes, if they locked him up I’d vote for him for certain
It isn't enough to find Trump guilty of a crime. He has to have been treated equally under the law. The selective prosecution we've witnessed since his 2016 election has been simply un-American.
I have tried to go on the assumption, based on the very narrow proposition in the OP, that any trial(s) that produces a conviction and prison term for Trump would be fair. It is to be assumed that if he were convicted of anything, there would be appeals of several different kinds, reviews, challenges, etc. Again, I'm just approaching the OP at "face value" and trying to avoid the 'bait' of being sucked into endless rabbit-holes of 'whatabouts'. It has been made perfectly clear in the whole "Russia, Russia, Russia" fraud, and two impeachments -- which were shoved through by radical Democrats without even enumerating a single, actual CRIME, that the Left in this country would do anything imaginable to destroy Trump. But, nevertheless, I have chosen to take a simple approach to a very simply-written OP and avoid all the subsequent 'click-bait'....
I never voted for Trump. I voted for Johnson in 2016 because my disdain for both Trump and Clinton was so high, I wanted my vote officially registered as being against both. I wanted both to lose, there was no lesser of two evils or a candidate I least wanted to lose choice between them. I voted for Biden in 2020 because this nation didn’t need a 75-year-old man who acted and behaved like a 4-year-old spoiled brat with his name calling and throwing of temper tantrums occupying the oval office. I think Trump revenge tour getting rid of any Republican elected official who isn’t or wasn’t 100% loyal to him only enhanced my disdain for him. Trump wasn’t, isn’t worried about the good of the Republican Party or the nation, only what is good for himself. Trump’s revenge tour has pretty much guaranteed the Democrats remain in control of the senate and will add 3-4 governors this midterm. Trump has been a huge help to the democrats with his revenge tour. What amazes me is most Republicans can’t see or don’t want to see how much Trump has hurt or is hurting the GOPs chances this midterm. To answer your question, I’d never vote for Trump whether in jail or not. But if I were a democrat, I’d be on my knees thanking Trump for preventing the red wave that should have happened with a president whose approval rating is around 40%. Thanks to Trump, the Democrats are in good shape for November.