Ok, so the problem here is not your lack of experience with knowing how to push a few buttons in the Revit interface, but how to use the tool effectively to do a few things:

1. Coordinate trades

2. Utilize powerful techniques within Revit to develop workflows that save time.

3. Construct BIM models that are actually constructable in American dimensions and technically feasible in the US.

4. Often times item 3 above is not entirely possible without having some sense of the American building codes and standards.

So naturally, any employer would not just look at whether your know the Revit interface (that’s the easy part), but rather how you can employ it in real life. It has been my experience that many people graduating with Master’s in Architecture these days have ‘YUGE  gaps in their technical knowledge and as time goes on, this problem only gets worse. We have so many people who think they can do a BIM model because the muscle memory from using softwares like Rhino and Sketchup is so prolific in new graduates, that naturally, they can fool themselves into thinking they can also model in Revit. 

So when you were denied a position due to a lack of experience in Revit, just know that there is probably more there than you think; it’s just not just the interface the employer is concerned you know or not…

You won't be able to learn Revit well enough on yourself to offer value to an employer. That's because the processes used to work effectively nowadays can mostly be learned by working at a practice with more experienced users, and not through online videos. Also, another problem you are dealing with is that construction methods / systems used in the US are different from what you learned in your education in India. It's best to know first what you are drawing as opposed to knowing Revit. 

Are you aware there's an Autodesk Revit certification?  You take an exam, passing gets you a certification from Autodesk.  It is industry standard evidence to demonstrate your Revit capabilities without US firm experience.  

https://www.autodesk.com/certi...

But before investing time on the Revit certification, consider: when I interviewed recent grads, I don't look for candidates to come with useable skill.  This is not snobbery, but reality is that we need recent grad to be moldable (teachable, curious, diligent, pays attention...).  Real use comes after they've learned "our ways".  So the best recent grads are those who learns and adapts fast. 

If a recent grad comes with a couple of years experience using Revit, I expect I'll have to unteach the bad habits they pick up in other firms, I'll worry they'll think they know what they are doing and implode my model, I'll still send them to Revit basic training....

If this firm rejected you for lack of Revit experience, that suggests they are looking for a Revit drafter, not a young architect to mentor and grow.  Proceed with caution.