Yes, it would still in reality be rape. No question. In a legal context however, I believe it would be much easier for the defense to argue that only theft had occurred, since the victim voluntarily reduced the act of sex with her to a service to be purchased. The perpetrators then simply “stole the goods” without payment. Still wrong, still rape, but law and the courts don’t operate on a system of right and wrong. They only concern themselves with the law.
The defense might try a “theft of services” argument. But the prosecution will still go with rape. The prosecution will go with a theory that the four men talked about this before hand and that one of them called with the initial offer. Upon her arrival he enticed her to stay with the prospect of earning more money. Then the call was made to let the others know she arrived and they proceeded to rape her. The prosecution will argue that the men involved never had the intent to pay her and that it was a gang rape planned from the start.