You really need to consult with the best attorney you can find. These are serious charges, and what they say they are going to give him may, in fact, be very different from what he actually gets. I believe the statute of limitations on drug charges on the federal level is five years. This means the government has five years to bring a case against you. But, I suspect the case already has been brought against you since you fled ( your cousin, I mean). So, the statute of limitations that applies to how much time the government has to BRING charges against a defendant isn't really relevant if charges have already been brought and he simply fled from them.

However, even if the statute of limitations expires, there very well may be other crimes he can be charged with that dovetail with the drug, conspiracy, and fleeing charges.

You really need an attorney. Don't act based on anything read on forums on the Internet--including this one.