It won't have any impact on your visa, they don't check and there's nothing illegal about a Canadian citizen owning a C corp anyway, Ted Rogers did it.
It's entirely lawful to run money through it and pay yourself from it as well, you report your personal income on 1040NR until you become a US resident. The immigration issue is only relevant insofar as where you physically are when the work is performed; where the corporation you work for is doesn't matter as far as immigration goes.
But bear in mind if you work for a US corporation it must be registered in Canada and have a business number and perform Canadian payroll withholding in order to be able to pay you, because you live in Canada.
Your real problem isn't the US end anyway, it's the Canadian end. If you own a Canadian corporation that is a CCPC, the CCPC status depends on your Canadian residency. If you cease be a resident of Canada you run into two big problems: (a) all corporate income becomes subject to the full rate of corporation tax - you can get out of this one by paying yourself more so the corporation has no retained earnings; and (b) the bigger problem is that you will be subject to departure tax.
Departure tax is a 25% capital gains tax on gains over $50,000 that are subject to the tax; (principal residence in Canada is exempt). So if you have a corporation that you started from zero and the balance sheet now says it's worth, say, $120,000, you are the only shareholder and if that's your only asset subject to the tax, you owe the CRA 25% of $70,000.
The way around it obviously is to reduce the value of the corporation so you don't get hit with it, but money you pay out will be subject to income tax so you have to time it carefully and also plan it carefully.
Read:
http://www.cra-arc.gc.ca/tx/nnrsdnts/nd ... n-eng.html
Steve.