Welcome to BYC. Glad you decided to join our flock. X2 on Wyandotte7's answer. Eight to ten years is about the most you can expect for a chicken raised in good conditions, although occasionally a chicken will live to be considerable older than that. The record life span for a chicken is 22 years. Please feel free to ask any other questions you may have. We are here to help in any way we can. Do you have Light Brahmas?
Welcome to BYC! Please make yourself at home and we are here to help.
Like the others have said, how long a chicken lives doesn't depend on breed but on health. The average chicken lives 5-8 years. But any chicken can live longer if they are healthy and properly cared for.