I think 7 years is definitely enough to be a senior but it depends on your experience. If you have worked for Google last 7 years it’s very likely you have been

I think 7 years is definitely enough to be a senior but it depends on your experience. If you have worked for Google last 7 years it’s very likely you have been promoted 3-4 times and have a lot of experience with large scale production systems. So I’d definitely say such person is senior.