Gerrymandering leads to disenfranchisement, which leads to lower voter turnout by the opposition, which then leads to his election. You see a similar thing happen in Texas as well because people think "oh my vote doesn't matter, why should i vote anyway?"
Tbf he's done a lot to disenfranchise those he doesn't agree with or make it harder for them to vote. All bc that side can't believe they're not popular anymore.....