To 'pitch for' something means to try to persuade other people to give you something. A 'pitch' is a speech or an act that tries to persuade someone to give you something or to buy something. You can make a 'sales pitch' or 'pitch an idea' for approval. "In Hollywood screenwriters and directors make 'a pitch' to producers in order to obtain the money for their films to be made." You might need to 'pitch' for a promotion in order to convince your managers that you are the right person for the role.