I used the Ewa Marine DB bag on my X-e2. The casing is almost exactly fitting on my X-e2 with little extra so I bet the X-t1 will also fit. The only problem is that while its rated for 20 meters = 60 ft, around 45+ ft or so the pressure starts to compress the water casing to the point that buttons are either continuously pressed so that the camera may be unusable.
After two dives with if I feel comfortable diving with it again that it won't leak. However without a hard casing the underwater pressure exerted on your camera may render it unusable until you come up a few feet to release the underwater pressure on the buttons. That being said I am actually flying out tomorrow to hawaii and will be diving so I'll let you know how it goes and maybe i'll put up some photos on here.