I am no pro at making jerky but have done it a few times and been very happy using
this recipe. It calls for low (or lower) sodium soy sauce. I just checked my fridge and saw that my regular Kikoman sauce has 960 mg sodium per serving vs 590 for their lower sodium version. I would guess you could also just cut back on how much you use.
I'd also suggest you poke around to see what the low sodium soy sauces there are - maybe you can find one with even less. If you live somewhere with a good asian market, you will find there is a HUGE number of different soy and other sauces out there. If you are in or near the twin cities, head over to Shuang Hur market on south Nicollet/eat street for a huge selection.