Sometimes. India is not always a day ahead of the USA. There is a 24 hour clock.
Student or Learner
We say "They are ahead of us". So do we say "They are behind to us" or "behind us"?
As you know sun rises in India prior to Usa. So can we say "We are one day ahead of Usa" or "Usa is one day behind us"?
I'm not a teacher of English, but I have spoken it for (almost) all of my life....
You have to be more specific. India has one time zone, whereas the continental US has four. Therefore India, today, is nine and a half hours ahead of New York and twelve and a half hours ahead of Los Angeles. As most of the US is on Daylight Savings Time and India is not, the time difference will decrease by one hour on November 2.
Please remember that the name of the country you mentioned is the USA, not Usa.
"They are x hours behind us" is the way to say it.