If it's a new t,couple (fitted and tightened correctly) and a good flame and still keeps going out it sounds like a faulty gas valve.does it keep going off or was it just the once after the new t,couple?
Pilot injector may be choked,does the flame look o.k. the pilot top (popes hat) aims the flame onto the.t,couple can face slightly off or burn through completely. It may be hard to see but does the flame hit the t,couple