Is it okay to bathe a cat with people shampoo?

It's definitely ok to bathe a cat once a week. As for using human shampoo, assuming it's not loaded with chemicals (like special shampoos for straight hair, curly hair, dyed hair, etc.), human shampoo is ok. (Although, I personally like Doctors Foster and Smith Oatmeal Shampoo for Cats. It's what I use to bathe my cats and it's really inexpensive and leaves a great smell.)

I have to admit Ashley gave a great answer! So I actually have nothing else to add!

Yes it is ok to bathe cat's with human shampoo as long as it's just normal shampoo.

Why do it?

Leave the poor cat alone...

Cats take care of their own hygiene, and no bathes are really necessary. 

I do bathe my two cats, but only 2-3 times per year.  They're pretty clean animals, all things considered [ESPECIALLY SINCE YOUR CAT IS AN INDOOR CAT]. 

My first recommendation is to NOT bathe the cat so often.  However, if he insists, human shampoo is OK only occasionally.  Since he's doing it weekly, strongly suggest getting a cat shampoo.  PetCo or PetSmart or any of those kinds of stores have it.  You're risking your cat's skin's health with human shampoos - that's for our hair; they have fur.

someone said leave your cat alone but i say it is a good thing i have 2 solid white indoor cats and give them a bath once a month because the get looking yellow you cant tell on dark coats and as far as useing people shampoo that is what i use

If you really need to bath your cat and want to use human shampoo, I'd recommend baby shampoo. It's not expensive and is much milder than most human shampoos. Remember to rinse thoroughly since cats lick themselves and you don't want them eating soap and chemicals.  Cats who are bathed too much can get skin problems, chills, or just get annoyed since you are subjecting them to an unnatural form of cleaning.  Bathing cats is generally a waste of time anyway unless your cat has some kind of special problem or long fur that kitty can't keep clean.

I've had long haired Persians and Himilayans for over 12 years now and bathe them frequently with human shampoo.  I also use conditioner on them so that their skin is protected.  Works wonders and has never caused any problems!  I do agree with not using shampoos loaded with various chemicals.