what happen if my dauther get pregnant at 16 years old, and her boyfriend is 23 years old,and he his not legal in unites states

The boyfriend is not guilty of a sex crime unless he held a position of authority, such as being her teacher.  The child will be a citizen of the United States.  The father of her child will have an obligation to pay child support and possibly the medical cost of the birth of the child. The father's rights will be determined in part if there is a recognition of parentage, but he will not have an right to parenting time, much less custody, unless he goes to court and establishes it.