She can be saved if you don't mind separating her from her flock for the several months that it is going to take to heal that wound. She will need to be isolated, with daily wound cleanings and dressings for several weeks. She can heal from that, but isolating a flock animal is a particularly cruel situation for them to be in. Unless she is really special to you I would cull her.
I had a hen survive a wound worse than that, but when she healed her flock refused to accept her back and she needed to be re-homed for her safety. Months of isolation, horribly disfigured after healing, a secondary infection she had to battle through. I saved my hen for me, not for her because it would have been kinder to just put her down.
Let us know what you decide.