I'd pull the lever to kill one person immediately. Assuming the decision maker at each stage is a different person with different opinions on moral, ethical, religious, and logical questions, then it's a near certainty that someone is going to pull the lever to kill the people at their stage. If you're lucky, it's the very next guy. If you're not, it's the guy killing a million people a couple of iterations later. If I'm the first guy, I'll take the moral hit to save the larger number of people.