ye a i think a gradual change to the area is better, the long any one faction hold the zone the more and more it begins to become full of the race controls.... looks and such

This seems like an interesting idea, I love spamming spores in Natural Selection 2 to where nearly the whole map is covered in green (insertwhateverthatstuffishere). I also agree for the idea with the orks. Let them have spikey bitz everywhere to show who's da biggest and da baddest!

and I think that the influence should slowly increase over time, providing minor bonuses to the controlling faction. Maybe Space Marines can have some good 'ol fasion holy concrete around their base! As for the eldar, meh, just put snow around them I guess . Or maybe put a webway gate here and there.

I cast my vote, but just to emphasize: YES. This is a good idea that really needs to happen.

I realy like the idea of the maps having some mark of who they belong to or who has captured them.
for the space marine faction their respective chapter banner gets placed on strategic pots, for orks their respective glyphs, Chaos marines got their respective banners and marks, for eldar they got banners to dont they? maybe if tyranids are infesting a area there will be capillary towers and such things.

I like this a lot. I was recently playing Black&White 1 and 2 again (if you are "good" your territory changes slowly to become a meadow with flowing grass and is quite peaceful. While if you're "evil" the ground becomes cracked and burnt, showing lava and the likes.)
I know those are single player but I think that having that gradual change depending on which faction is holding it how long that faction holds said area for would really help immersion.

Imagine wondering with your squad and you look down and suddenly you're like shit, this is ork country!

Hope this gets further consideration. If (x) faction captures a territory, its appearance should change to be fitting to that faction.

If i remember correctly they said in the live stream something about flags and banners showing who is in control of the area. Think they also said something like skeletons and such.

This would definitely be a nice idea, but seeing how even the Tyranids are apparently to retarded to invade the overworld and instead are locked to being an underground nuissance, I wouldn't put to much hope into it. The respective "starting" zones will undoubtedly be visually influenced by their respective faction, I doubt that contested territory will change its look. I mean, they didn't even manage to do expandable bases.