Lost acceleration while driving now the truck won't start. And when I popped the hood it smells like gas

Is there a fuel leak under the hood perhaps preventing the engine from getting fuel? A concern where the engine will crank but not start indicates a problem with one or more of a few areas. First, you could have a fuel delivery problem. You could have a lack of ignition spark. Engine timing could be disrupted. Engine compression could be compromised. Proper air intake to the engine could be interrupted or too plentiful. Testing hands on is required to find out what is happening.