It is not permissible for any Muslim to join in the festivals of the non-Muslims, whether by attending the festivities or enabling them to hold their celebrations, or selling any goods or products that have to do with these festivals.

If your work involves helping the company in any way with any kind of cheating or stealing, then it is not permissible. But if your work has nothing to do with the haram things, and the company also has some other departments that do not deal with haram things, then it is permissible for you to work in the departments that deal with permissible things.