I'm not sure why the T-34 would be considered underpowered. It's essentially 1/3rd the cost of a Tiger or IS-2. It should be much worse and lose 1-on-1. The T-34 is meant to be a mobile tank used for killing infantry and light vehicles, then for ramming lategame to disable heavy tanks.
I do believe side armor could be a good addition, but a map like Pripyat is a bad example. No one likes Pripyat competitively. It'd be better to relate side armor to matches on Kholodny, which is actually a reasonably well-balanced 1v1 map, or Oka/Moscow for larger games.
However, in the end, Pripyat is a map people will play on. Furthermore it was chosen to demonstrate this issue exactly, to show that it can be exploited in one's favour.
If you are at a choke point with a tank which possess good frontal armour, all you would need to do is expose your front half, with your ear half being blocked by the 'bridge's walls'.
I actually possess a reply where 4 T-34s are up against 1 tiger, due to clever usage of the environment the Tiger barely got penetrated, in fact in the replay you could see I was hitting the side of the Tiger, but it was closest to the front, making the round bounce off. (as stated in the original post)
As a result I had to sacrifice one of my T-34...
It's a good thing it was for fun