Its income period. If you are reasonably frugal any sort of "real" programming job is enough to handle the loan payments.
But no matter how frugal you are a $40000 debt is unlikely to be paid off on $10000 in funding. You would be making a big bet not only on a success but a timely one. So yes I think student debt is a large deterrent for those who have it.
(Although if you think that a job at a big company is guaranteed income, you've never worked at a big company going through any kind of hard times!)