Depends which refugee destinations we're comparing. The bulk of the Syrian refugees end up in neighbouring countries, not Europe. Turkey has already absorbed millions of them, using them almost as slaves to run its economy. Others are in Jordan, Lebanon, etc, in refugee camps. I'm not sure most Venezuelan refugees would want to stay in neighbouring countries, though. So this problem might become mostly America's, and you are right that it is potentially bigger than the Syrian refuge crisis, because Venezuela has almost twice Syria's population.