I've interviewed at Facebook 2 1/2 years into my career and have an open invitation to interview whenever I want without having gone to a tier 1 university for undergrad or grad (although I went to a prestigious program for grad math, UIUC) - my education turns out to be a poor indicator of what I can do.

A caveat is that I originally entered FB's pipeline through a referral from a friend who interned and works at FB right out of CMU computer engineering. Referrals are often enough at these big tech companies.