How much can an international student earn in the USA?

Basically there is no limit on how much you can earn working part-time in the USA. It's the work hour permit that binds you to work for long hours. Because as an international student, your focus should be on your selected course there instead of earning while studying. The ministry in the USA henceforth put a limit on work time.

Basically in the USA, you can work 20 hours a week based on various factors. The first one is your visa. The student visa particularly allows you to work 20 hours a week on the campus of the university. Don’t worry, once you get there you will find enough part-time job options. They do not require any skill sets and are also very comfortable.

The second way of working part-time in the USA as a student is a work permit. The time limit for a student remains somewhat around 20 hours a week. By the way, I just want to clarify that all these don't include vacations. For example, if you get a few days off due to some festive or a holiday season, you can work for long hours. 

For earnings, it is mostly between $7 to $10 per hour based on the level of work and experience. For example, if you have some previous work experience, you can get jobs as customer support or various such roles.  These pay more than the regular ones that are mostly at fast food joints, departmental stores and assistant jobs.

If we take the average earning of $8 just to be safe, you can basically make $160 a week and hence around $650 a month. This is equivalent to around INR 50,000. I believe it’s enough to keep your expenses at a manageable point. With this amount, you can almost manage your cost of living in the USA. 

With this, I believe you can calculate yearly earnings. Or even differences based on the types of jobs. Let me know if you need some more help.