Ranvir - I am not based in India so I cannot tell. But I have seen quite a few of their outlets in Mumbai and Delhi - all at prime places. Rentals are likely to be much higher than your estimate (but so could the revenues). Even generally, Tata global’s (consolidated) EPS has been the following:
2007: 7.5 2008: 24.9 2009: 11.3 2010: 6.3 2011: 4.1 2012: 5.8 2013: 6.0 2014: 7.8 2015: 4.0
They have outstanding shares of 63cr. Even with your profit estimate of 150cr. (in a few years) for Tata Global from the Starbucks franchise, that will hardly move the needle by Rs 2.5 per share. In a company that hasn’t shown any EPS growth over the last few years, just this alone doesn’t look like a very compelling reason to invest - just looking at the numbers.
The string itself suggests that this is a discussion on your portfolio, so obviously it is entirely your call but all investment must be done with full DD.
Best.