There are reasons to believe so.
- Oda has said in an interview that he is a fan of Eminem. Oda has designed many characters appearances based on real life people before, it's not unreasonable to imagine him doing the same for Enel.
- Enel was introduced in 2002, which was at the peak of Eminem mania. It was the year that The Eminem Show was released, and a year after The Marshall Mathers LP. Eminem was absolutely massive at that time. It's like, Oda just happened to draw a character who just happens to look like the biggest star in the world at the time?
(Just saying, Eminem might seem like a random person to base Enel on, but if you take the context of the year when Enel was introduced, Eminem was at the top of the world, so it doesn't seem like a random person to base a character design on at the time.)
Stole this from a reddit post but it makes sense, also I prefer calling him Eneru because it sounds like energy like the lightning he channels