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.

• Even if you pursue a B.tech degree from IIT Bombay (an old and reputed IIT), the institute never succeeds in maintaining a cent-percent placement record. You can even cross-check the stats from IIT Bombay’s website.
• Students studying mathematics and computing students from IITs, most of them are more inclined toward research careers than jobs.
• M.Stat degree from ISI is unique in India. The course is highly reputed and the institute itself is far ahead of most Indian institutes in the field of stats, math, and economics.

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.