Some of the Chick fil a locations give free food on your birthday and some of them do not.
It's all up to the individual Chick fil a location because every Chick fil a location is a Franchise that is individually owned so while one Chick fil a may offer free food on your birthday another one may not.
If the Chick fil a location gives free food for your birthday it's usually just on certain months so some people may not get free food even if it's their birthday.
Some Chick fil a locations also sometimes offer $3.00 off of the purchase price of any ice cream cake.
If the Chick fil a did give everyone free food on their birthday then they might end up going broke because most likely everyone in the world has a birthday on everyday of the year.