How to become a U.S. citizen?

I have a cousin that was born in Mexico but he came over to the United States when he was a year old.He’s 19 years old now. He’s been living here since and graduated from high school a year ago. When he was in high school he was assaulted by a group of guys and got his jaw broken. Also, while he was in high school he got two tickets one for curfew and the other for trespassing. The problem is that he hasn’t paid them yet. Would that affect him getting his citizenship?