Hello all!
I have successfully used my Fuji XT-1 with EKOS, to control the shutter release of the camera. I haven't tested the image capture thoroughly yet. The shutter release i am using is based on a digispark attiny85 stump.
You can find the code in topic DIY PROJECT: Digistump Attiny85 Remote shutter release . Flash it using the arduino IDE as usual.
Under ekos, make sure to set following options in the EKOS control panel:
camera tab -> main tab ->
-- shutter release -> enter the port where your arduino/attiny connects and click set
-- connection -> click disconnect and then click connect. This is necessary for EKOS to update the port.
camera tab -> image settings
-- encode -> native. Since the Fuji cameras use an X-Trans sensor, They arent really compatible with this set to FITS
camera tab -> settings (you need to scroll as this tab is close to the end)
-- priotitymode -> camera (Set your camera to Bulb mode. This is to switch the camera from 30" to BULB mode. This should reflect on your cameras display. You may need to set ISO on your camera manually)

Thats it! Use a relay module or a transistor circuit connected to the pin specified in the code (standard is pin 2 as this pin is connected to the second onboard led) shutter release wires of your cable, and you are golden!

Edit: Testied and Working!