So, this will almost certainly be considered a new play for the Tony Awards, and that is probably the correct decision.
BUT, just because I'm in the mood to be nerdy and pedantic, I'd like to point out that the play premiered back in 2013, and had a few productions that were completely unaffiliated with the National Theatre's production. According to Wikipedia, it premiered in France in 2013, which was followed by an Italian production in 2015. It wasn't until fall of 2018 that the National took the existing play, had it translated into English, and re-conceived it into its current form. SO, given that the play had already been produced independently for several years before this production came into being, one could make a case that TECHNICALLY, the National Theatre's production was a revival of Massini's play, and by extension, this Broadway production would be a revival.
But I understand that all this happened in a relatively short span of time, which was probably not long enough to consider something a revival under the "classics" rule. I just think it's kind of an interesting alternate take on the situation.
Anyway, move along!