People usually dont realize but all top b-schools in the world are "research" based - which means that the key criteria for promotion/tenure of faculty is research output. No b-schools in India follow that model. Yes, faculty at IIMs and other Indian b-schools do publish research, but almost nothing in top business journals. Unless we adopt that model, no Indian b-school will achieve top tier ranking.
Ambani's offer is a good initiative. But for a sustainable solution, we cant depend on just one person to finance international research faculty. Eventually the solution will have to emerge from the institute/government itself. Also, I dont know where the article is getting it's number from, but no b-school professor (asst/associate or full) is getting anything less than $ 8-9,000 in US. I'm guessing IIMs will have to offer someone at least half of that (Rs. 2 lakh PM) to attract anyone. And more than that for more renowned names.