Blockstack is an architecture which supports gaia storage, wherein the blockstack api supports routing the Blockstack identity via the BNS naming system to the users gaia hub, where they own and store their own data.

Gaia is not necessarily dependent on Blockstack, but it was designed to be modularized within this design, so users can control where their data is stored, which is not necessarily the case with IPFS.

It is pretty darn cool :)

Let us know if you have any more questions.