The accompanying article (linked in the quiz and worth reading) says they won't reveal whether there's a minimum number of correct answers to be hired (and they don't take the quiz all that seriously either, especially now that people can look up the answers on their phones). I got 38/50 without googling, which I suspect is not quite good enough.
I can only get 9 without guessing (and I didn't try to guess at the others). For some reason I feel like I'd do better if they had listed the full author name and not just the last name.