My "banana" was a bit over 12 when she died. I have a group of seniors now, about 5, 6 and 7 and going strong. and 6 years and going strong so far. A couple are no longer laying but I keep them and let them live out their lives after giving me such wonderful legs. Also I'm very much a suburban chicken mom as they all have names and I have a vet available when I need to. I've heard some folks have chickens living into their teens.
My oldest is a 6 yr old cuckoo marans named Nestle. She was the second one in my flock to start laying this season and is going strong at about 3 eggs a week
My Lilly is at least 6. I rescued her from living under a porch back in 2015. She lays about 3 to 4 eggs a year. I wish she would stop laying all together. She is a wonderful alpha hen for my flock.