The question was, "how much does publication status matter?" The answer is, unless it is accepted/published, it doesn't mean anything. You don't get brownie points for something being in revision or being submitted. I had an extensive basic science research background when I applied to medical school. I sat on an admissions committee reviewing both MD and MD/PhD applications. Nowhere did I say that someone would be rejected because they put down that something was "in revisions". It simply won't help either.
Outside of accepted publications, what counts is what that research experience imparted on the applicant. The average MD candidate or MD/PhD candidate does not have an extensive research resume and we rely on students to explain to us their research experience and what it means they bring to the table. But, having something "in preparation, submitted, in revision" etc is meaningless. You are coming at this from an applicant perspective, not from an adcom perspective. Most of us that have been involved with research for some time, (personally over a decade now) know what that means. We have also seen dozens, if not hundreds of students up-sell these things to try to make their applications stand out. There is tremendous value in research experience outside of publications and I, as virtually all other adcoms, recognize this. But, when it comes to publications, they really are all or none because there is no way of checking until it is actually accepted.
