can ivern counterjungle??

Would take too long and he'd be fucked if he got caught.

with smite up, ya

Yes he can. Like Riot had said " It only takes Ivern a few moments to lay down or harvest his grove on camps, so he has access to jungle routes that just aren't an option for those who have to fight and kill their prey. One valid strategy: Take Smite and Teleport, then go into the enemy jungle and drop a ward near an entrance. After sprinting through and gettin' grovey with all the camps, TP back to the starting point for another lap to set the whole zoo free."

As far as I can find their no way to stop his pass from working once he use it beside killing the monster outright but he can all was use smite then to set free all the monster. Not just use it on one of them like a normal Jg.

I just watched the 1st game of them playing him on the PBE in their live stream. he went to ther other teams Red and stole it in like 3 seconds ganked top for 1st blood and got his blue buff all within 2 minutes 35 seconds of the game.

So your answer is yes lol. He also finished 15 - 5 - 25 and game didnt even go 30 minutes i believe.

you can watch it here

https://www.twitch.tv/leagueoflegends/v/90468486

game starts around 34 min mark