So I have and A in one class but a D in the other can they still revoke my acceptance letter
Yes. What does your provisional admission contract state as your conditions to maintain your acceptance?
It ultimately depends on the college and the course, but getting a D raises a risk of your admission being rescinded even if you have all A’s and B’s otherwise. It may actually result in an automatic withdrawal of admission if it is in a course needed to complete the prerequisite courses for admission to the college, e.g., the college requires satisfactory (C or better) completion of 4 years of English to qualify for admission and the D is in your fourth year English course. As to other courses, the degree of risk of withdrawal of admission varies among colleges.
We’re a little less than half way through the school year. Get a tutor ASAP and get that grade up, even if the best you can do by the end of the year is a C.