|Your cousin is correct in trying to run the family business as a business and not as a family. However, if that is truly his goal, he needs to listen to his employees, whether they are family or not.|
This means that your next step is to meet with him. Prior to such a meeting, try to identify some specific situations where it would have made more business sense for your suggestions to be implemented. When you meet with your cousin, show him some specific ways that he and the company would have profited by listening to you.
He needs to understand that your objective is the same as his, namely to focus on business and not family. When he overlooks you, he is actually making a business decision based on family considerations. That is not fair to him, to you, or to the business.
Be sure to ask for his thoughts on how to deal with this matter. He may have some specific ideas, or he may say that he will try to be more responsive in the future. Either way, if you look at what he does in the future, you will know if there is a future for you.