An employee costs the company in four ways: Salary, taxes, benefits, and capital.
Salary: The obvious one, what they pay you.
Taxes: There are several taxes that an employer has to pay for the privilege of hiring someone, including social security taxes (which goes to your retirement), unemployment insurance tax (your unemployment benefits if they lay you off), and workers compensation tax (pays if you are injured on the job). (There may be other taxes that I'm not thinking of, but in any case those are the main ones.)
Benefits: In the U.S. employers often pay for medical insurance, sometimes for dental, life, and disability. There's usually some sort of retirement plan. They expect to give you some number of vacation days, holidays, and sick days where they pay you even though you're not working. Companies sometimes offer other benefits, like discounts on buying company products, membership in health clubs, etc.
Capital: Often the company has to provide you with some sort of equipment, like a computer; furniture, like a chair and desk; etc.
As far as the company is concerned, all of the above are part of the cost of having you as an employee. If they would pay a domestic employee $60,000 in salary and $20,000 in taxes, then assuming the same benefits and capital investment, if a foreign employee would cost them $0 in taxes they should logically be willing to pay $80,000. Any big company will have accountants who figure out the total cost of a new employee in excruciating detail, and they will likely be totally rational about this. A smaller company might think, "well, taxes don't really count ..." This is irrational but people are not always rational.
I don't know what benefits they are offering you, if any, and what equipment they will provide you with, if any.
I also don't know what taxes, if any, a U.S. company has to pay when hiring a remote employee in a foreign country. If anybody on here knows the answer to that, please chime in.
Balanced against that, the company likely sees disadvantages to hiring a foreign remote employee, too. Communication will be more difficult, which may result in inefficiency. My previous employer used some contractors in India and while there were certainly advantages, the language and time zone issues caused difficulties. There are almost certainly some international bureaucratic inconveniences they will have to deal with. Etc. So while you should certainly calculate what it would cost them to have a domestic employee doing the same job, that's not necessarily the end of the story. And ultimately it all comes down to negotiations. Even if the company knows that by the time they add in taxes and benefits and whatever, a domestic employee will cost them $100,000 a year, if they are absolutely convinced that they should be able to hire an Austrian for $60,000 a year, that might be the best offer you will get. You can point out the cost savings, and maybe they will concede the point and maybe not.