The first option is correct. You don't need to repeat "die in" as it is obvious from the context. You also don't need to repeat "you will". You would never use the second "that". "Than that" do not go together, you only have to say "than". The most natural option would be "It is much more likely that you will die in a car accident than a plane crash"

Shane, but could I omit "that" and "die in" but repeat "you will"? Like "It is much more likely that you will die in a car accident than YOU WILL in a plane crash"? Or maybe if I repeat both "that" and "you will" , but omit "die in"? "It is much more likely that you will die in a car accident than THAT YOU WILL in a plane crash"? Does (or DO???) neither work?

It is much more likely that you will die in a car accident than in a plane crash. There is no need for the second "that", or to repeat "die in". You would not use "one" at the end, and I would say you need to repeat the "crash/accident", however, plane accident doesn't sound natural and is referred to as a crash. Therefore I would say... "It is much more likely that you will die in a car accident than in a plane crash". But as Michael says above, the saying is generally... "You're much more likely to die getting to the airport than you are flying in the plane".

What if i omit both just "die in"? Like: "It is much more likely that you will die in a car accident than that you will in a plane one"? .............Or maybe if I omit both "that" and "die in"? ... like: "It is much more likely that you will die in a car accident than you will in a plane one "? Does(or DO?????) neither work?

"You're much more likely to die getting to the airport than you are flying in the plane." -source, discovery magazine "You are more likely to die in an airport than on an airliner." -source "the week" magazine