Would anyone be able to tell me why a health boost to the faction with the smaller population wouldn't be in order? More health generally means a greater ability to tank multiple foes (while utilizing skill) before you go down, which seems to be able to directly help problems like this. What am I not seeing?

The first mistake is a belief that if a faction is less populous then it should be 'balanced' in some way to make it competitive. That's comparable to the Refs in a game of soccer saying "Yeah, one team has a lot more people on it's roster, so, for the smaller team, we're just going to ignore all their penalties, since they have to work harder."
That's the wrong attitude.
Also, look at it this way, the larger faction is going to have to deal with battle happening on more fronts, at more locations, and will have to deal with Tyranids in the backfield. On top of that, there will be more of a drain on faction resources as there are more players using them, where the smaller faction can focus more.
There should NEVER be any direct "buff or debuff" because of population imbalance.

Agreed. Sometimes there HAS to be a losing side and like the Devs have been saying this entire time, it will just be how the players/community handles being in the position that they are in. If the Orks are stompin, perhaps it is time to be aside animosity between chaos and imperium to make sure that they both survive to kill each other later.

There can never be enough wolves.

Good job !

Thanks for the answers.
W8ng for a new information

will we be able to in the future create our own chapters

also can we play as dreadnaughts

Hahaha so damn true xD

Independently of the result I want to thank you for trying more than 2 or 3 factions (4 currently planned) in pvp.