What is the most an international student could earn at a US grad school? I haven't gotten any offers yet, but I just got an e-mail from one of the biggest names in my field (engineering) who urged me strongly to apply to his school. This, along with a few other factors, makes me feel it's likely I will get admitted to one of the top schools if I choose to apply. This is humbling, exhilarating, amazing, etc, but the caveat is that I have a family to support. 

We have barely scraped by for too long now and it would be really nice to give my spouse some measure of financial comfort. So, counting everything including stipends, scholarships, allowances and every other trick in the book, what would be the most one could hope to get from a place like MIT, Stanford or Princeton? 

I think most people here understand how valuable a PhD in engineering from MIT is in terms of future prospects in both academia and industry. Would it be crazy to consider supplementing ones income with a loan in order to live decently, if not doing so would mean being forced to decline the offer altogether?
I can't answer your question directly (probably no one can), but I have some first and second-hand knowledge. This applies to CS/engineering in the US:


I've had several friends that went to Cornell, Princeton, and Stanford and they have told me that they make around $28,000-$34,000 for a 12 month salary. However, the cost of living in places like Stanford is very expensive, so you need to adjust for that (there are calculators online).
You can do an internship at a company or lab and make around $30,000 in a single summer. 
Most funding agencies and departments won't allow you to double dip. So receiving external funding (e.g., a fellowship) would replace, not supplement, your assistantship with your department.


In ideal circumstances, this means that you could make 25k (9 month salary) while at university and another 30k during the summer, for a grand total of $55,000 before taxes.

Of course, you have to be careful because internships aren't guaranteed and you may have to relocate to another city/state for them (often paid for by the company) which might pose another challenge for your family.