Yes. But to what extent depends on age and amount of use. When you are developing at a younger age, it slows down development making it harder for your body to produce sperm cells, but it is less of a problem at a older age. There is no way smoking weed will stop you from having children. Although it could increase the chance of a defected sperm cell which could lead to a deformed baby, but this is extremely unlikely.
I don't know about the sperm count but it may cause shot-term memory lose but just certain things and not like the movie 50 first dates
Hell Yes I would Know!!!! Either have Kids or smoke weed your choice!!!