I've 3.5 years of experience in IT. Is it worth joining KJ Somaiya for PGDM-core course? I'm expecting above 8-9 Lacs package, is it viable?

Your experience is good. But apart from experience there are alot of factors that affect your final admission. KJ Somaiya is definitely a good choice but to secure yourself look for other top rank colleges and apply in them too.

Usually, you get paid according to your caliber not by your college. And coming to 8-9 lacs that is the maximum package you can expect from KJ Somaiya, thus, its unlikely to get such high package for common student.