The TLDR answer is that he doesn't believe that the constitution gives the federal government as much authority as they exercise.
I'm mobile, so I'll try to make this brief, but in _Sessions_, for example, he expressed concerns on how vague or poorly written laws afford the government too much power. In _Gutierrez_, he (unusually) wrote the majority opinion, and then also a concurring opinion that I assume he couldn't get other justices to sign on to, which effectively bashed Chevron deference.
_Chevron_ was a case largely believed to have set the stage for much of what people see as abuses of federal authority holding (basically) that an ambiguously crafted statute that does not expressly give a government agency over an authority over an area, but which could maybe sort of be interpreted that way, then you should find in favor of the government, because they're the experts.
Gorsuch believes that giving the government powers that Congress did not expressly intend is an abdication of judicial duty, and that we shouldn't interpret ambiguity as a blank check. He thinks that if Congress intends to give <agency x> authority over a specific domain, then they should say that explicitly.
TLDR, the deference that Chevron establishes as precedent in government cases most largely benefits agencies operating under the executive branch. Trump runs the executive branch, so that cuts in his favor. Gorsuch believes (more than the other justices) that they do not deserve that deference, and that laws should be interpreted to mean what they say.