When it comes to the tenure review process, someone puts it like the way it's put below:
The tenure review process is designed to determine whether someone has "the ability to do their job." The junior faculty member has six years to construct a track record of success. During these six years, the junior faculty member acquires teaching evaluatons from students and colleagues. The junior faculty member acquires grants and sets up a lab with a productive research program. The junior faculty member develops a reputation of collegiality and service within the department and the university.
Though that's how it's done in name. Others, like Sean Carroll, say that research is far more important than teaching (which is probably true in the elite private universities).
What about things like successfully graduating PhD students though? Can a PhD student help an assistant professor gain tenure? I'm particularly curious about whether or not this applies for all universities - both in the elite privates and the public ones.