The DNC has successfully gamed the system. We are losing state after state. Trump may not win again. What happened during the Midterms was pure theft and the GOP rolled over. This is partly why they are so furious that Clinton lost. They thought they had her in the bag.
Those are only related in the sense that Trump voters can overcome geryymandering. if htey turn out. In 2018 there were more non-Trump voters and the gerrymanders worked for the D's. Even some R gerrymanders went to D's.
But if Trump get outs the vote, that gerrymandering won't stop us from taking back the House, easily.