With the fx reserve, it can either support rupee or buy gold. Not both. Also, i don't think buying gold strengthens a currency, when a currency has no fixed gold pegs to begin with. Gold is just another competing form of money, it is not the backing of any other money. 

And if India prints rupee to buy gold, the effect will be the opposite 

spiderman

econ

Rupee gains ground with central bank help

It depends what they're goals are. I think the Indian central bank could pretty easily boost their currency. They'd just have to increase their gold reserves.