Are these formS correct?
The first is fine, except for the fact that we'd probably say 'a hundred' rather than 'one hundred'. We mainly use the numerical 'one' to specify a certain number i.e. one rather than two or three. But as nobody lives to be two or three hundred, there's no need to say 'one'.
The second sounds less natural. 'Till', or more correctly 'until', is usually followed by a time expression (e.g. until 5 pm) or a whole phrase ( e.g. until you've finished). We might say "Some people live till they are a hundred years old", though.