I don't think you need to "forward" the env variables, they're automatically added to the environment.
So you just need GAIA_DIR="`pwd`" (please use double quotes to prevent any space-related breakage)

Also, this is nitpicking, but maybe using GAIA_DIR="$(abspath .)" (or replace with realpath) works? And maybe it's worth it to have it as a top level var called PWD?