Nope, that would be "nejedí" in Standard Czech.
Though, it's somewhat common to use "jí" for 3rd person plural as well, at least in Common Czech. Personally, I don't like it and would advise against using it. Adds unnecessary confusion and sounds extremely sloppy. O:)
I left out the word "too" which was accepted but certainly in english that changes the meaning (ie 'it does not eat much' implies eating little, whereas 'it does not eat too much' implies not eating to excess). So I'm wondering which is closer to the meaning in the czech sentence?