An estate executor is paid by the estate. Her compensation is drawn from the estate's assets. The amount of compensation due to the executor is determined pursuant to the law of the state where the will is probated, or pursuant to the terms of the will.
After a decedent dies, an executor is the person tasked with, among other things, ensuring that the estate is properly probated, the assets are distributed among the beneficiaries and estate taxes and debts are paid. These duties require attention to detail and can be quite time consuming. As such, the executor is entitled to compensation.
When determining the amount of compensation due to the executor, it is important to look to state law. Some states use sliding scales, some use percentages, and some states merely require a "reasonable" fee.