My boyfriend was born without a pituitary gland and we will see a doctors for when ready, but in theory can he have kids? hes on hormone therapy and what not?

Because the Pituitary gland hormones control puberty and male reproductive development, if your boyfriend is receiving gonadotropin hormone replacement, he should be able to produce sperm and father children when he is ready. He is old enough that he should be able to discuss this with his medical team and achieve a good understanding of any problems he may be facing with this condition.