Gaia (Greek mythology) The earth, daughter of Chaos, both mother and wife of Uranus (the sky) and Pontus (the sea). Her Roman counterpart is Terra. Γαῖα • (Gaia) (genitive Γαίας) f, first declension. (Greek mythology) Gaia or Gaea, the Earth personified as a goddess. Of uncertain origin.

So as many other things from old Greek, this is not a greek word. It is borrowing from pre Greek, or Barbarian people. Probably from the north of Balkan peninsula.

Gaia was originally only used as the name for the land along okeanus potamus, sea river, Danube. So it is perfectly possible that origin of ia is gaia. All i wanted to know is that there isn't any Slavic root for it.

Great thanks.