1B doesn't happen in one day, so who is close to hit that is the question.
Twice's biggest songs seem to be around 500M, and it's for songs that are 3-4 years old. From what I see, they are the closest, but it might take another 3-4 years.
i dont see anyone but bts and bp hitting those numbers as of right now. maybe twice or itzy in a couple of years or so since twices most viewed mv has around 600 mill?