There's been a few who've got xeljanz off-label with UC. One who had great success was user suzy-q, here's a thread about
her story on it, 2016:
/www.healingwell.com/community/default.aspx?f=38&m=3600816Here's another thread, with users StewieCat and Loopchic1978 who are also taking xeljanz for their UC, 2017:
/www.healingwell.com/community/default.aspx?f=38&m=3925101As far as insurance, I would expect a denial on first try as it's currently off-label. You can get an approval on appeal with your doctor's help. He/she should be able to help you through the process.