You say "my son"----which is confusing for us. If your BF is your son's biological father then yes, he can claim the child as a dependent and get child-related credits like the child tax credit and maybe earned income credit, as well as file as Head of Household. If you lived with him for the entire year (by the end of 2025) he can also claim you for the non-refundable $500 credit for other dependents.
If your BF is not your child's father, then he can only claim him as a "qualified relative" dependent if the child lived with him for the entire year. But if BF is not the bio-father, then he cannot get the child tax credit, earned income credit or HOH filing status by claiming your child. He would only be able to get the $500 credit for other dependents.
IRS interview to help determine who can be claimed:
https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
