Not sure how you come to that conclusion. So far, no swing states have flipped since 2016. I suppose we can feel good about having a strong polling lead in WI+MI, so Biden just needs PA or AZ to flip the election (if my math is correct, PA would certainly do it).
So it's not about gains, margins or national vote count (conservatively, you can already guess Biden will have well over 6M more total votes). It's about the Electoral College, and so far tonight, there's nothing that really supports your assertion. Too early to call IMO.
Remember coming into tonight, Nate Silver/538 modeled that Biden had about a coin flip's chance of having the election called in his favor before the morning (in other words, he was going to blow well past 300 EC votes). Unless something drastically changes in GA or TX, it looks like we likely won't know for days and that plays into the corrupt incumbent's hands. But again, too early to say even that until more votes are counted in the Rust Belt.