If you were a monkey, would you sacrifice a billion humans to save a monkey?

Or equivalently, would you sacrifice a billion humans to save a robot that's twice as sentient as the average human?

I cannot really say what I would do if I was a monkey, it's like asking me what a circle with corners would look like. Too far outside my ability to imagine. I wouldn't sacrifice any number of humans to save any kind of robot either, unless it was a robot critical to human survival like a surgical robot in the middle of a natural disaster.

Would you save a monkey whose body contains antibodies for the cure for cancer for humans (or AIDS/HIV/whatever), or 1 human?

The monkey. The answer would be the same for just a vial of the antibodies, the monkey is completely incidental.