Do people on linux side stil irc ? or is irc completly death ?
A strange question. All you have to do is try it yourself. There are several networks with countless channels. Depending on the topic they are well to very well frequented.
Just because antergos only has had a gateway, endeavouros only had an unofficial channel, that means nothing. There are even projects since IRC is one of the most important or the most important communication channel, for the latter e.g. siduction (a debian sid based distribution - I use it - siduction even has a link to the main channel directly on the desktop of the live image).
Not everyone wants to use Telegram or similar social media offerings.
IRC can be used easily, whether it makes sense to use it via a client of your choice or for short things on any computer with a browser via a web gateway.
If you are often in certain networks on certain channels, you should register your nickname.
I would rather ask why XMPP (Jabber) is so marginalized.
Just general 
For me, the early 2000s were a big time for the IRC. 
i think irc is to nerdy by using special commands to do stuff, in a compartment to funky new ones all over with emoticons, gif, voice message, video … most users today think system is broken if you do not have a nice GUI shown up, and IRC you can use on a serial console if you want… no need for any gtk qt ui GUI … so in former times i was happy to have this if i need some help on fixing my system…
Today? i can take my smartphone and research for a solution, or a layin around tablet…
so true as today i use quassel on my pc & pi and my phone, quassel is especially on my pi but Telegram is a good medium. as today i am more on it, got whatsapp for my coworkers and family but just failed to switch over to telegram… old is not always badn they find it to old. i generaly hate if i am on pc the need of a phone, thats funky… so no removal for whatsapp further i dont keep to much but im stil online on irc
I never used IRC, but I did use Newsgroups heavily.