I had Citrix Receiver working on funtoo linux a while back, but made some changes and could not figure for the life of me what it was. I thought perhaps Funtoo was not stable or there was a conflict with the shared libraries.
I decided to install
strace and the problem was this. Citrix Receiver will happily wait indefinitely for the directory
~/.ICAClient to exist before confirming if you accept the EULA because it wants to save your preferences.
Please make sure you do
mkdir -p ~/.ICAClient and you'll be okay.