If playing against a Viktor, or any other hitscan champion, try flanking them, because they will have a longer time to react to the damage, and you can unload about two shots before they will detect you and start firing.

Because Viktor is a hitscan champion, he should be able to deal with Drogoz quite good

Viktor has a hitscan weapon, meaning the bullets will immediately hit Drogoz, so he effectively counters Drogoz.