is twitch jungle still viable this season

I don't know if it's every been efficiently viable.

every aggressive jungler just invades and kills him.

outside of that he needs so much gold and hes extremely item dependent that he wont be ganking other lanes.

he would need to have a very high success rate on ganks, or competence from all the laners to ward and not lose turrets in order to work even with pressure from the enemy jungle.

then yes, twitch jungle could work, he would be a hyper carry late game, but at the same time your initiation and peel isn't on your jungler, so that leaves top/support to do near all the peel for the team.

TL;DR: yes it can work in very unique situations, but its not something you want to try, ever, over the multitude of other jungle picks out there.

Several reasons why I'd say no.

1. Devourer isn't as good as Flare was for Twitch
2. You can't leash the buff nearly as long as you used to be able to, so Twitch no longer is able to clear the jungle without taking several hits.
3. He was already highly vulnerable to invades and counterjungling, and point #2 exasperates this weakness even further.
4. Another byproduct of the same point is that he now has worse income due to slower (And worse) clears.
5. Even bot lane Twitch is kind of weak and outclassed right now. In the jungle, he offers extremely little to justify him over other junglers.

Add to this the fact that the jungler is expected to, if not be a tank, then at least have some durability and CC, and Twitch becomes even more undesirable in the jungle. If you needed even MORE reason, he has one of the most expensive builds in the game, being an ADC. In the jungle, you already get less gold, but he gets even less because of the sheer inefficiency of his clearing speeds.