I think Gia-J sounds jarring as the J sounds are too close together. I agree it sounds like someone chewing. My suggestions:
Gloria Jasmine "Gia"
Gloria Juliet "Gia"
Genevieve June "Gia"
Gemma Jordana "Gia"
If you really want Gia as a full name (which I think is fine, plenty of people opt for Mia) then you might want to break up the J sounds:
Gia Annabel June
Gia Eloise June
Gia Summer June
Gia Emily June
OR go for a J name that actually starts with a Y sound. Like Gia Juanita.