Had the same idea a couple weeks ago and went over AMD's past couple quarterly financials.  Could not get a real clear picture as to what portion of their revenue/business is directly related to the popular mining GPU lines.  Someone with a little more experience with AMD records might have a better idea.

 While I do think it is significant enough to increase their numbers for Q4, I don't think it will be as influential as it would for an actual card manufacturer(HIS, MSI, Saphire ect.) Unfortunately the couple I've researched are private companies or part of large foreign holding groups...