I have heard that UChicago waitlisted a couple thousand people, but did everyone in the waitlist get the the gap year offer? Or is it only selected students (Z-list in case of Harvard). Also, what are the chances of having a seat in class 2022 if one agreed to the offer? Is it a guaranteed ( Or semi-guaranteed) admit?
Everyone who is waitlisted is offered the gap year option. The gap year is not guaranteed; the admission officers will chose the applicants that they want for the class of 2022 (think of it as another, smaller admissions cycle). If accepted then you are for sure in the class of 2022 as long as you remain in good standing when you graduate high school (as with any admission offer).
I think I read before that the decision occurs in June of this year for class of 2022??