Volumio looks for drives/shares available on your local network, and there is not a simple way of using your Google Drive as a source. However, I suspect that it could be done with some fiddling around at the command line in Volumio. Have a Google for “Google Drive site:volumio.org”, and see what you can turn up. Here’s one link to get you going Cloud sync on external drive .
Edit: to be clear, you do want to access files on the G-drive, and not on the SSD drive?