Yes, it does, IF you are a recruited athlete and being offered a slot and receive a Likely Letter.
How much it helps with grades/test scores or your Academic Index (AI) varies depending on the sport. Some sports only have a few slots/Likely Letters available with football receiving the most slots/LL and typically having the widest range of AI bands.
There are sites online that will calculate or estimate AI which may give you a sense.
Of course, it will also vary within the Ivy League by school as well. An athlete can be a recruit at one Ivy but not getting any interest from another.