Strijkbout: Assuming it's the DOS version of X-Wing I can only guess that maybe you have other controllers plugged in.
There are several ways to solve this, the easiest way is to unplug unneeded gamecontrollers, another way is to open the Windows gamecontroller panel and click advanced and see if your controller is the preferred device, and the last way is to edit the Dosbox .conf file with notepad and change the joysticktype but it can only swap between a total of 4 axis so it may not be the best solution.
Hmm, I'm using a Gamecube -> USB adapter with two ports, so it's possible that it is being detected as two gamepads. I'll see what's happening on that front. Unfortunately I'm on a Mac, so I don't have access to the Windows gamecontroller panel ;) It would be helpful if there was something like that incorporated into DOSBox...
Waltorious: If you are running one of the DOS versions that uses DOSBox, you can try using the DOSBox keymapper to map keyboard keys to the buttons. Check this video:
https://www.gog.com/forum/star_wars_xwing_and_tie_fighter_series/xwing_1994_tweak_guide_video_graphics_sound_music_speed_and_controls/post1 May not help if the game isn't responding to the gamepad thumbsticks though.
Hmmm, I'll see what I can figure out, thanks.