How do I cite an article which has been accepted pending revisions, but the revisions aren't accepted yet?

"In revision" might be a good option for some venues, say when referring to the work in a presentation.

The most closest thing you could refer to would be to consider your article as unpublished or submitted for publication.

In APA style:

Authors. Manuscript Title. Manuscript submitted for publication

In IEEE style

Authors, “Title of paper,” unpublished

IMHO, the best strategy is to upload the preprint version to an open archive such as arXiv or archives-ouvertes. Almost every journal accepts this (check sherpa.ac.uk/romeo in case of doubts).

This way, your work is accessible to everyone instantly and freely, nobody can steal your work and, more importantly in your case, you can cite it. Just mention Preprint and provide an url or, nicer, a clickable link. You can also mention Submitted to ... for example.

Of course you can upload the author version or even the publisher's version if allowed (check the above link to know), once the article has been reviewed and accepted.