There's no activity on every account I managed to find that belongs to him - github, reddit, nixers. On each of them there's more that one year of inactivity.

Anybody knows he's still alive?

I'm not sure what's his state right now.
It's true that there's no activity on reddit, the account seems to have been deleted, on nixers it dates from 2016, and github 2017, but that doesn't necessarily mean that the person is dead. There's a lot of people in this community that move on to different things, or switch nicknames without telling anyone. The fact that the profile is erased on reddit proves this a bit.
You can check if dkeg is still active on LinuxBBQ and on the blog.
Also, I'm not sure it's appropriate to dox and trace dkeg if there's no IRL relationship, people should be free to control their online persona without telling others.

EDIT: his personal domain has been updated via his personal email just recently in 2018. So he probably moved on into something else, you don't need to worry or it could've been auto-update.

He uploaded tons of brilliant ricing setups and his github contribution graph looked worrying to say the least. Thankfully he's ok, thanks for information.