Turning on an optocoupler through a long cable

I'm curious if my cable choices are limited by this design. The MCT62H has a maximum forward LED current of 20 or 30mA, and it works perfectly well on the breadboard with a momentary switch. 28AWG wire is only about 0.065?/ft, which is insignificant over these runs, but I was thinking it might be a better idea to use data-oriented cable, which I believe are often around 110-120?/ft (or /m?). Anyway, I'm planning on using an XLR interface so I don't have to worry about a flexible cable getting damaged.

The question is will any sort of cabling over that length dissipate too much current to turn on the LED in the optocoupler.

Cables don't dissipate current - they dissipate voltage. If your cable is too high resistance that will limit the amount of current that can flow: (5V - Vf)/(470 + cable resistance + switch resistance) = 20mA. So stick in Vf for the LED, do a little algebraic manipulation, and adjust the 470 if the cable resistance is too high.

Be sure to use a pullup resistor on the arduino end for the optocoupler to pull low so yo have a clear change of level. The '328P internal pullup should do.