Yes, I do believe he can win. I said well before the democratic primary started that Biden was the candidate most well positioned to beat Trump, and nothing has changed. Oh, btw, Trump believes that as well. That's why he had his campaign people concentrating on Biden even when Biden wasn't looking all that good. The first thing that the far left and far right need to do is forget about their feelings about the other candidate. For some reason neither side can understand how anyone can vote for the moron on the opposite side. Well, the polarization of the electorate has made it perfectly clear that Barney Fife would be able to rally either base. So in order to assess the race, you need to only look at the numbers. About 40 states are already locked into their candidate. That leaves both candidates with just a little over 200 electoral votes guaranteed. And that's giving Ohio to Trump. If Ohio becomes winnable for Biden, Trump is in real trouble. The same is true with Florida. There are very few scenarios that Trump can win without Florida and Ohio. But the real battleground states are Wisconsin, Michigan, and Pennsylvania. Biden is way more popular than Hillary was in Pennsylvania. I would be surprised if it didn't flip. Michigan is also leaning that way and Trump's threatening to withhold aid is not helping him there. If they both flip and the map remains basically the same as last time, the electoral race will be razor thin. Independents in Wisconsin, Michigan, and Pennsylvania gave Trump a very thin margin of victory in 2016. They may not feel the same way in 2020. Trump has a huge advantage in money so that is in his favor. He can dump tons of advertising into those states and it would probably do him well to focus on Wisconsin, Michigan, Pennsylvania, Florida, and Ohio. The rest of the country he will either likely win, or has no shot at.
There is also the prospect of a third party candidate that can divert votes from either candidate. That would likely hurt Biden more than Trump. Jill Stein took votes that would not have gone to Trump in the last election. At best they would have stayed home. A progressive independent candidate would go a long way to hurting Biden's candidacy. I don't see anyway a third party candidate would damage Trump.