how can i buy tidal subscription from india
If the service is not available in your country, then it is not available in your country.
Going around this is just as bad as piracy and is considered so. Therefor, this goes against the forum rules.
I think the best advice is for you to use another similar service provider that is available in your country.
A quick search shows that the following services are available: Apple Music and Spotify.
If you want Tidal specifically, make your voice heard to the company, and with enough similar request, the company may evaluate the market potential, and may stay talks (if they haven't already) with the different music publishing companies in India, and those with publishing rights in your region, and all other legal requirements to offer their full service. If the music associations in your region costs too music for Tidal, just says "No", then you are out of luck, as much as the company in bringing their service to India.