Yes, they do, but nowhere in the series is the Gaia/Earth Mother referred to as a deity. If she was, I think people would call on her like they do the Creator/Light.
He did for everything else.
When he is about to step into Shayol Ghul proper, the DO speaks to him for the first time in the book, and he has a thought line that he's heard that voice once before.
Page 431 in the hardback.
"IT IS TIME. LET THE TASK BE UNDERTAKEN.
The voice spoke with...