it means: Fine thanks, and you?
Thank you
"Ganz gut soweit und dir selbst" would be the reply to the question "Wie gehts" or "Wie geht es dir?". "Wie gehts" or "Wie geht es dir" translates as "How are you" (informal). "Ganz gut soweit...
I hope all is well with you.
Ich bin immer ganz gut translates as I'm always very good (at doing something)