It depends on the article, if it has been reviewed and is waiting to be published you can cite it as "author (year), title , in press"
however if you the article has not been given any reviews then its not a good option to cite it because we never know if the article will be accepted or not..
IEEE hasn't prescribed any format for article under revision so I am afraid you may not be able to include it in your list.
further I would request you to follow the links below which may help you to get answers to your question.