I don't think he died. I think he just left Imgflip. At this point I don't know if he will come back or not. Hopefully he will though. But he is probably still alive.
I know It's going to take a few months, but Raydog is in danger of losing his spot on the top 250 leaderboard to Iceu. He already lost the #1 spot. It happened before I joined Imgflip with my first account, but it was sad. It will be even sadder if he loses #2. In order to save him, we have to upvote his images to give him more points.