I expect we'll see massive, record breaking turnout. Normaly only about half of registered voters vote, but I think it will be closer to 65% or more this time, and I think that will give Trump the edge. Pollsters often filter their results by only including "likely voters", and that are people that voted in the last election, which misses the people that Trump has energized who normally don't bother with politics.
There is always voter fraud and the deep state which we saw drawing a federal salary in the FBI, and if they underestimated Trump last time, they will be working overtime this cycle to make sure Trump doesn't go a second term. But it's going to be popcorn crazy.