air travel – Can a visitor visa person enter into US from India via Mexico?

The ban is not on “Indians”, but people who have been in India in the last 14 days. The same applies to many other countries (all Schengen Area countries, the UK, Ireland, Brazil…), and to any person who is not a US citizen or permanent resident or one of the few exempted classes.

So you could indeed travel to any country which is not subject to a ban, stay there for 14 days, and then travel to the US.

US visas do not have any restrictions on where you are coming from, so you can indeed enter the US from Mexico if you want to.

Note that you should absolutely not try to pretend you weren’t in India in the last 14 days if you were. They will ask, and it is extremely likely they will find out, and they will be very unhappy, cancel your visa right away, send you back to where you were coming from, and this will be a big black mark on your record.

Note also that even airside transit counts as presence in any of the countries subject to the ban, so transits via most European countries also count as time in a banned country.

Finally, you should of course check any restrictions and requirements for entry into the other country (Mexico in your question), and that you will need a recent PCR test before you can board a flight to the US (and most other international flights, really).