Oculus Rift hasn't disclosed how much ownership was transfered in its Series A and Series B funding [1]. Also Carmac's Salary, and possible investment isn't disclosed [2]. John Carmac is estimated to be worth ~4 million [3], source seem to agree.
<pure speculation>
His salary wasn't disclosed, but with 75million being spent in Series B funding it seems unlikely he was a major investor. Any equity he had was likely given partially as compensation for his position.
</pure speculation>
[1] http://www.oculusvr.com/press/oculus-vr-raises-75m-in-series...
[2] http://www.oculusvr.com/press/john-carmack-joins-oculus-vr-a...