Potentially further than you could feasibly manage on a regular bike. This is because, while not as much effort is needed to ride an e-bike, many tend to cycle greater distances on them given they have preserved more energy, and so make more use of them.
Of course, though, you are limited by the battery life of your electric bike. These are designed to be fully charged overnight so that they can be used every day, and can also be remotely charged virtually anywhere where there is a plug socket or computer.