I think this post is closer to the truth than the post which suggests once you’re in, you can slide through. While I never taught at an Ivy League school, I have taught in the Big Ten and my experience is that very few (if any) profs let students slide through simply because they got in.
Universities spend millions of dollars trying to recruit minority students. They spend millions more providing special assistance to keep them enrolled. Flunking minority students is frowned upon. Flunking any full tuition paying student is also frowned upon. State schools may have a different protocol.