resumbitted paper proper citation
I think the few different statuses you would typically indicate are:


Submitted: after submission but before you’ve received any indication that it’s being reviewed
Under review: during the entire back and forth of reviews, revisions, rebuttals, etc.
Forthcoming (also called “In press”): once it’s been accepted but hasn’t yet been published.


As for formatting, it probably doesn't matter much as long as all the relevant info is there, but a few options to consider are:


  [1] A. Author et al., Brilliant Title That Draws Attention, J. Phys. B, submitted August, 2019. Under review. [arXiv:1908.12345]


or


  [1] A. Author et al., Brilliant Title That Draws Attention, under review at J. Phys. B, submitted August, 2019. [arXiv:1908.12345]


I'm sure you can find other examples elsewhere (such as this post).