I think they are just lucky to land on their feet – perhaps their instincts are better than ours. They don’t have 9 lives though, I think that’s just a saying because of how lucky they are to land on their feet!
Cats have a natural righting reflex which helps them to determine which direction is up and down when they are falling through the air. This helps them land on their feet most of the time. In addition, cats have a very flexible backbone which enables them to land safely on their feet.
Cats only have 1 life. It is because they appear to escape injury free despite falling from a height that they seem like they have 9 lives!