Having served as an executor before, I can tell you that an executor earns his fee. In most jurisdictions, an executor (or administrator if there is no Will) has a legal right to a fee. However, the Will may say something different. In some cases a testator will address the issue of executor compensation, particularly where family members are serving. Further, some jurisdictions limit by statute what fees an executor may take.
You need to look at the documents -- the Will, and the law in NJ. Since I am not licensed in NJ, I can not give your specific advice in this regard. Do you know how much your brother plans on taking? Do a cost benefit analisys; if you are successful with challenging his taking a fee, will you net more money than the potentail fees for hiring an attorney? Also, if you challenge it, he may be able to pay for his attorney fees from the estate as a cost of the estate.
You should review the documents with an attorney who is familiar with NJ probate laws to determine if your brother is eligible to take a fee.