Hello oodoominoo
You can get a discount, but usually only for full price tickets. You can also buy semi-flexible or non-flexible tickets. Buy these tickets on sbb.ch and indicate that you have a GA when you define the passengers. The system will show the different prices.
You can also buy your tickets from Basel to Paris on sncf-connect.com and use your GA from Zürich to Basel. You can compare the price with SBB.
Kind Regards
Danhiel