alt Hacker NewsUse College Navigator for these types of questions:
https://nces.ed.gov/collegenavigator/?q=MIT&s=all&id=166683#...
That link says 72% of incoming freshman in 2022-2023 received financial aid. Also has a full-time beginning net cost average of just under $22,000 in 2022-2023.
It's not a perfect source of data, but there is enough on College Navigator to let you dig into it a bit and compare to other schools.
Note that aid includes federal student loans though. They may have needed to come up with $22,000 out of pocket but also have taken on thousands more in loans that will need to be paid back. If they don't have the $22,000, then private student loans at much worse terms are likely required.