The Russians supplied India with armaments when America refused to sell them, and even forced Britain to stop such sales - one of the Soviet premiers famously gave India’s Nehru tours of Russian aircraft factories with promises of supplying India with the latest of Russian weaponry - at a time when the West refused to entertain any such efforts.
The American bet was on a religiously “cohesive” Pakistan to survive over the long term, in comparison with what was thought to be a very unstable, secular India. On top of that, the Russians quite early on shored up support for India in booting out French and Portuguese territorial claims from within her territory - especially Goa.
Things turned out quite differently, for all parties, through the years. India, no doubt, acted in India’s interests and stuck with it.