How many Oscars did Alfred Hitchcock win? Did he ever win an Oscar for Best Picture?

Zero if you are talking about "Best Director". One if you count Best Picture.

His film Rebecca won one for Best Picture. You may or may not consider that a 'win' for Hitchcock.

He was nominated for five (5) Oscars for Best Director but never won these nominations.

He was awarded the Irving G. Thalberg Memorial Award for lifetime achievement in 1967.

https://en.wikipedia.org/wiki/Alfred_hitchcock

No. He was nominated for Best Director 5 times (Rebecca, Lifeboat, Spellbound, Rear Window, and Psycho) but never won.

His film "Rebecca" won Best Picture, but as director, he was not a part of that award. https://en.wikipedia.org/wiki/List_of_awards_and_nominations_received_by_Alfred_Hitchcock#Academy_Awards