Can a guy who had leukemia, and got cured, have a child?

Yes, possible: Yes. Will depend on the age, other treament/bmt?- that affect fertility. Fertility can be affected in about +/- 50%- with certain chemotherapy for leukemia.It is important to talk about fertility prior to starting chemotherapy and have something done like- spermcryopreservation etc- if time allows. Many times- there is not enough time to do those as treatment for leukemia has to be started asap.

Infertility: Up to one-third of adults who undergo fertility testing after having been treated for cancer or leukemia in childhood or adolescence have suspected infertility. Patients and their parents should be counseled about the possibility of infertility and about fertility-preserving measures.

Leukemia & fertility: There is a dose response curve of chemo agents that could potentially effect sperm or egg, and there is also an age response when exposed to the chemo agents. Specifically a woman's eggs were created prior to her birth, and they are at risk to damage throughout her life, whereas a male prior to puberty has immature sperm cells which are more to damage by chemo agents.