@CUsucceed If you are talking about common data sets then for example MIT does include the accepted students from the wait list to the accepted students overall. For example in their blog it says that last year they accepted 1410 students but then in their class statistics they state that they accepted 1427 students and that 17 were accepted from the wait list. This is true for a few other colleges that I have checked.
Wait list students also count in the acceptance rate. For example here it is from Bowdoin’s announcement:
“Bowdoin’s regular decision admittance rate hit an all-time low of 8.3 percent for the Class of 2024, down from 8.9 percent last year (9.05 percent after students were accepted off the waitlist).”
I am not sure about the overall yield. I would assume that wait list acceptances have a very high yield as some colleges accept students from the wait list after they call and ask if the student will attend if admitted, give only a few days to decide and accept in waves.