The USA (including Alaska) has about 3 times the land area of India, so India has about 4 times the population on 1/3 the land, or 12 times the population density, but I don’t think even that implies India cannot support its own population.

Their GDP per capita is about 1/30th of that of the USA, or about 2/5 of that of the USA per km², and I think that’s a better way to approximate land needed than raw population size.