One of my best engineers at my last place (and still someone I consider a good friend) was an Indian citizen. I was only tangentially involved in the process, and I suspect your guy would fall under different classifications and eligibility, but regardless here's how that went to the best of my knowledge.
We hired the guy straight out of school, after finishing his masters at Johns Hopkins, under a program for STEM majors that granted an initial 18 months of visa eligibility, with the option to extend a further 18 months beyond that, so 3 years total. Pretty much knew at the time that's all that we were guaranteed to get out of him, anything beyond that he would have to apply for an H1B visa.
The way H1B works is through a lottery system, there's a bunch of paperwork to apply for that which needs to be done sometime around March each year. The drawing occurs sometime around the end of March/beginning of April and there's something like a 10:1 ratio of applicants to spots available, so not great odds. On the off chance someone who gets selected doesn't take their visa, that slot gets redrawn from the applicant pool, so the process drags on for months before you know for sure you missed out. Furthermore, I think you only get so many shots at it before you're out of chances, want to say 4-5 maybe?
My dude missed out on the H1B lottery his first few years and it was right around this time last year his initial 3 year eligibility was up. I was pretty upset at the prospect of losing him (as was he,) but after talking with a lawyer we were able to come up with a workaround and buy more time on a type of student visa by enrolling him in another degree program at the company's cost. There was about a 2 month gap where he was unable to work before classes started and the school got their end of the paperwork completed.
Then, this spring I was on vacation when he called to tell me he got selected for the H1B! Never been so happy to hear work news while off! I think that gives him up to another 6 years of eligibility, then I'm not sure what the next move would be if he wants to remain in the US. I know there is family pressure to move back home at some point, so that may still be the long term plan, but that's for him to decide.
All that being said, I would highly recommend talking to an immigration lawyer. I'm certainly no expert, far from it, just sharing what little secondhand experience I do have. YMMV, etc. etc.
EDIT: One more thing, there is also a fairly significant cost for H1B visa sponsorship on the part of the employer, something on the order of $10-20k IIRC. I don't recall if that's a one time thing or each year you apply or are eligible.