To my survey taking experience, I've qualified several times. It really depends on honesty and how much time and patience you have in it. Sometimes, you'll get lucky and pass, and sometimes, you wont be as fortunate. I usually spend 30 minutes to an hour depending how many I've qualified, but once I start disqualifying for 5 or more of them, I'll stop and come back tomorrow. Videos are also great, but at least you'll earn some GC.
I used to love earning from Game Coins, but it seems it's no longer available. :c