I don't have any current statistics comparing the job outcome and earnings of students graduating from elite and more average universities. ... but I do have some thoughts.
When comparing leading public universities with the Ivys and Ivy-like schools, you can find outstanding faculty and courses in both locations. A mature and focused student can get a lot out of either university. But, in reality, most college freshman are influenced by their peers. If a student is surrounded by others who are extremely high performers, who fully expect to graduate and go on (as reflected by high retention rate at the school), then the student is likely to take the classes more seriously.
If the student is exposed to a large number of students who aren't absolutely committed and find the idea of "dropping out" ok (as reflected by lower rention rate), then that student may not treat the college years as seriously.
I'm not an advocate of elite schools for the prestige, but for the kind of expectations that students approach them with. I have a daughter at Stanford who is elated to be surrounded by a population of motivated students - each with some cause or interest to which they strongly interested or commited. Alcohol is present, but it hasn't been a "hobby" for her friends, because they're all too busy knocking themselves out for classes and all of their special interests.
A second set of benefits associated with elite schools is related to the research opportunities that are EASILY (very, very accessible) to students. Any university offers opportunities to work or perform research - for the motivated students. The elite schools generally go out of their way to give students multiple opportunitites to take classes from and work with leaders in any field. The result is that the student can have a very, very advanced idea of what he or she wants by graduation time.
A second issue ---- many of the elite schools have large enough endowments to offer large scholarships to even the middle class - bringing the cost of education closer to that of public universities.
I'd like to hear some other thoughts.