Can Twitch become a jungler?
He's more of an assassin of a marksmen, and jungle Twitch was super viable in Season 4. His Q makes for great ganks (invisibility) and almost-mediocre clears (attack speed) but he has no sustain, defense, hard CC, or burst so he can easily die at first buff or have to recall.
What I suggest is his passive's damage be doubled against monsters and heal for the damage dealt. He would heal only a constant 12 health per second at level 1 (Machete is 7 and upgraded is 10) which isn't really much when you take Warwick or Nunu into account or realize he has no defense whatsoever and he's ranged so he has low armor.
I know I'm not allowed to compare him to Kalista because she's another champion but her E having Twitch W + E 2.0 is a big spit onto his face but changing his role and giving him strengths would help him become viable.