There are likely very few Indian nationals at the college per year relative to the number that apply (The HIO records only 22 Indian students across all four years at the College currently http://www.hio.harvard.edu/statistics) - although there are far more Indian-Americans at the College than that. I would trust Gibby’s judgement, and if we go off their estimate of at least a thousand applicants per year, that’s a 0.55% acceptance rate (5.5/1000)
International admissions have always been a degree more competitive than regular admissions at Harvard. The Indian nationals at the College that I know all have had exceptional characteristics - major competition wins, ECAs, overcome significant challenges, etc.