[firebrand]

I don't think "like" goes back as far as the fifties in the current usage. "She was like" in place of "she goes," for the even older "she says," had been around for quite a while before I first saw it in a novel: Ann Tyler's The Accidental Tourist.

[AnAmericanMother]

I can speak authoritatively that "like" as an interjection or "noise word" was very common amongst the "beatniks" in the fifties.

I was there, and they used it, like, every other word, man.

[arthurus]

It goes back to the fifties just as it is now used. I know; I was there.