I really do not like the name Karsyn or any variation of that name for a girl.
Carson for a boy would not be that bad, even a bit trendy right now. Try these names if he likes Karsyn, he might like these:
They are more girly!
Kameron;Scottish Gaelic meaning "one with a wry or crooked nose" (Kameren,Kamrin,Kamron,Kamryn;English variations)see also,
Cameron.
Kalina;Hawiian form of
Karen
Karina;Contemporary diminutive of Katherine,"pure."(Kareena;English variation)
Karissa;Latin meaning "dear one" (Karyssa;English variation)
Karmen;spanish variation of
Carmen