Shell spin through his potion to dodge damage and CC. Jump from side to side when you see him try to throw his snake. Damage him and hook him for the finisher, even if he uses his escape you should still be able to get him.
In a straight DPS fight, Vivian does more damage than Zhin. If you have Deflector Shield up, you're likely to win the 1v1. Be wary of his ultimate and Whirl, as both will ignore your shield and the latter can place him behind you.
The educated Strix player knows not to attack you when you're in Counter. The key to getting him is to fight fire with fire and be as stealthy and sneaky as possible; and be ready to react when he inevitably pulls out his sidearm.