My daughter's cat has just had it's first season... She is very excited about her cat having kittens and wants to know...

How many kittens does a cat normally have in her first litter?

Please help as I just don't know the answer.

Anything from 1 to 8 possibly the cat will only have a couple though if its her first litter

I had a rescued kitten once (about 6 months old) to have 6 kittens - only 5 lived. I had another stray not to long ago to have 5.
I know a few people who have rescued cats right now, one cat had 4 kittens and another had 5.
Also after they are done nursing their kittens, they go back into heat. Cats are either in heat, pregnant, or nursing kittens.
I always recommend spaying a cat to help control all the unwanted ones that result from their relentless breeding cycle.
Good luck with the upcoming litter.