Our 1 yr old cat just had 1 kitten and it died within 2 hours of birth at the vet hosp would this cat accept a kitten that is 6 or 8 weeks old?

To nurse it? Try it and see, but by 8 weeks, most kittens are weaned or almost weaned.

No, she will eat it.
No, she won't. If anything, she will ignore it.