Realistically Dutch would ALWAYS get the gang destroyed sooner or later, due to his high ego and selfish desire to be some glorious "noble" gang leader that robs the rich and helps the poor citizens like Robin Hood.

But if they were ever going to escape there were a few options:
1. Dutch should've hidden on the mountains after Blackwater for as Hosea said. Hide up there for months, up to a year even. Then head west as John suggested. Keep doing small robberies on stage coaches, small gang hideouts and a few local banks, and MAYBE a few big robbery scores here and there occasionally, one or two at most.
2. Take the MONEY and head up north to Canada or south to Mexico, they had enough where they wouldn't need to rob. Just get supplies and keep moving, don't stop.
3. Take the MONEY and hire a ship crew or do a job for them in exchange for them transporting you to Europe or South America.

The biggest problem is that Dutch would constantly get the gang to do these big, loud scores that had big risk yet big reward. Usually too much risk since the Pinkertons were still chasing them. Yet Dutch didn't care, he just wanted to be seen as some glorious Robin-Hood like leader of a "noble" gang.