Looking up is a technique you can use to teach yourself to avoid the bad habit of throwing your head down, which means not jumping up. In reality, once you understand the movement, you don't look up. But if you find that your instinct is to throw your head down too soon, not getting enough height for your rotation, then you might try looking upward at a 45 degree angle to ensure that you're traveling in that upward direction first.
It's true, your body has the tendency of following your spine. So, if you're looking up, you're less likely to flip down, which is everybody's problem.
So in short, if can help you. If, however, you're already jumping upwards, you probably don't need it. Its a very small difference.
Good luck.