All the momentum is currently on Donald Trump's side. According to the polls, Trump has made up nearly 10-15% in about a week, and went from being down somewhere between 8-12% in all national polls to being either tied or up 1-5% in them. There are still six more days until election day and Trump will still have to turn at least one blue state (such as Pennsylvania) to get to 270 electoral votes and win the Presidency, but it is not impossible.
I think it's entirely possible. The momentum is massive at the moment for him. The silent voters out there, can't be dismissed either. This is one crazy election to say the least.