The difference is at that point Hillary was polling around 44 or 45 and Trump at 39, the rest 16% undecided.
In 2020, it's 50-45 in the battleground states, and only 5% undecided. There's a lot fewer people TO move this time around. Trump has to get almost all the undecideds.... Good luck with that I guess, but Trump is not "running ahead" by any rational measure. More importantly, there was a lot of voter apathy last time with Hillary, and many didn't vote, but this time we're seeing record turnout, especially from Democrats, across the country, like we saw record Democratic turnout in 2018.
Obviously Trump can still win, but there's no objective reason to think so on this date. If something changes, his odds change, but it's going to have to be big. I doubt if Comey equivalent is around to open up another chapter in BUTHEREMAILS at the last possible moment, but you can never count out Consigliere Barr for some late day shenanigans.