a quote from a person with relevant expertise I know and respect can absolutely convince me to read a book I'm otherwise 50/50 on. No number of other quotes makes any difference.
If a SFF novel was loved by (for instance) Ursula LeGuin or M John Harrison I'm gonna read it. For nonfiction books I look for respected scientists or experts in that field if I'd recognize them (depends on the topic). I don't think I even parse quotes from names I don't know.