I have friends studying in ISI Kolkata and old IITs. Based on my conversations with them, I will say there is no doubt that M.stat students from ISI have better chances of landing jobs with really lucrative salaries. You will be surprised by the fact that ISI is known for its 100% placement ratio for M.Stat. This is not the case you would be able to find in any IIT whether old or new.
I have attached a video that will brief you on the ISI Placement scenario
Overall, ISI stands as a premier institute for fields especially related to stats, math, and economics with a 100% placement ratio.