I’m an employment attorney and handle these types of discrimination cases on a daily. She does not have a claim under any current precedent. The only base line claim that will make it past a motion to dismiss is age discrimination where all you have to do is claim that you are over 40 years old and were replaced by someone significantly younger than you. Simply arguing that you are straight and were replaced by a gay person will not fly. It’s an auto motion to dismiss that has not held up under any precedent.