Does papers under review/revision has any value for faculty application in mathematics ? In detail, when reviewing faculty application does the committee checks the content of the papers or just checks the journals where it is published ?
Yes. It's an anecdote but I got a permanent position pretty much because I had a paper under revision at a very top journal. It still doesn't count as much as a published paper, though.
One thing you can do is ask the editor if she/he would be ok with you mentioning it in a job application and whether you can pass on contact details so that the job committee can ask for confirmation. You also have to take the reports into account, moreover; an extremely positive report with some minor modifications asked is not at all of the same value as a lukewarm report with a lot of major modifications asked.