What, you expect people to go "OMG i love Russian imperialism now" because a poll on territories they are free to propagandize and terrorize after driving out a lot of opposition and restricting them from campaigning before the referendum indicated their imperialism was supported?
As i said, even if it was accurate (which it probably wasn't, as the same Gallup made a similar one
before the takeover with different results), that changes nothing in the grand scheme of things, because let's be honest, if USA went around third world countries and replaced the governments there with no real justification beyond making a questionable poll showing local support for that replacement few months after, you would be very quick to protest that.
But guess skepticism towards polls is something for you to wield just on face value, while other people aren't supposed to wield it against even most questionable ones if you like the result.