There are two people on this forum that do for sure, S is one of them (his daughter is about a year now) and Craig, who posts a lot in the families and adults section and also has a son with CF. Craig has Atypical CF, I don't think he knew about it until his son was diagnosed.
It's pretty rare, as I'm sure you know. Only about 2% of men with CF can have children naturally. There is also adoption or medical intervention.