The Leo DiCaprio character is a complete fiction. The real Bill the Butcher was dead almost a decade before the riots. The Old Brewery was torn down even before that. Unlike the movie, there were virtually no Chinese in New York until after the Civil War. And that's just a start of what the movie gets completely wrong.
Frankly, serious historians don't put much stock in Asbury's book, The Gangs of New York , either. He was more of a journalist cranking out pop nonfiction than he was a historian.
When I was a kid, I read Egyptian history books because I was growing up on Hollywood depictions of that era. I never believed that Victor Mature or Anne Blythe represented the royal family of Egypt! The important thing about these movies is to encourage interest.