In a lot of the comics, the future Superman has greying hair, sometimes a beard, so as far as I know, he does age. I don't think he ages the same as an Earth man does, though, because in most 'future' Superman comics, Lois and his family have all passed away. This also means that all depictions of Superman set in the future usually portray him as either crazy with loneliness, or arrogant and cynical having lost touch with his 'humanity'.