I don't speak french but the really stupid thing is there must be dozens of real words analogous to bigly in every language.

Like, alright, it's an intensifier to be used at the end of a sentence. It was used as 'we're going to win bigly.'

So...

We're going to win extremely(still awkward, this is definitely not the kind of idea you put at the end of a sentence in English. I couldn't articulate why, you just know it. ironically a second language english speaker has probably learned the grammar from the ground up and tell you exactly why it scana weird.)

We're going to win so much(much better and at his vocabulary level)

We're going to win immensely(same problem as the first one but probably closest to what he was actually saying using a real word.)

We're going to win stupendously

We're going to win unbelievably

We're going to win hugely

We're going to win amazingly(again, like most of these, it would be so much better to go "we're going to win, it'll be amazing" or "we're going to be amazingly successful", but this is what they mean when they say he has broken syntax).

Just all in all a man who does not have a mind for language.