The thing is that ahri pushing hard the first few levels isn't a big deal. Her roaming is meh if she doesn't have ult or the mana to spam Q to get there and back + fight, so she is pretty confined to lane until lv 6 minimum in most situations. When she pushes like that without ult she doesn't have an easy way to escape a gank, and trying to escape will generally cost a charm and Q, which is a good chunk of mana on someone who will go heal up in the jungle anyways. Viktor also has a lot of tools for farming under turret, so he doesn't suffer as much as most mid laners early.
Yes Ahri has the early tools to shove in, but she leaves herself very open when doing so, cuts her lane off from getting ganks, and she can't really do anything with it. So Ahri will generally freeze lane so she can poke more easily and only hard push when she wants to back or sees the jungler elsewhere and wants to bounce the wave.
So while Ahri can push in early, she can't do much with it nor does it hurt Viktor that much. As soon as Viktor has hextech, which is his first item, his waveclear is vastly superior to ahris.
Also Viktor can hit all 6 minions just like Ahri, and unlike Ahri he can stand away from the minion wave, so Ahri can't hit him and the wave while she has to stand in a position where it is easy to get hit with the wave, especially since she has to stay in line with the wave to make sure the orb hits all the minions twice.
What I don't get is what you are trying to suggest. Tyrek was looking for strategies to deal with Vik, I offered advice from my experience in the matchup. You then tell me that my advice is wrong, but I have yet to see you offer anything else. Viktor beats Ahri through farming and pushing. He does not have the roam of Ahri so he loses there. Ahri will also often beat him in fighting because she has the tools to avoid a lot of his damage. She can easily get out of 2nd E hit, W, and ult, while Viktor is an immobile mage, making him an easier champ to kill for a skillshot champion like Ahri.
The one way he is superior is his Waveclear. My advice was to utilize that as it is one of the 3 win conditions for a lane (Roaming, Farming, Killing) and the only one he is better at than Ahri.