Not a huge amount considering Golovkin-Lemieux did 150k. I think they can sell the Russia vs USA angle and do 200k+.
Russia vs. USA Ivan Drago vs. Apollo Creed Brawler vs. Boxer With some creativity and "a little" truth stretching you might be on to something.. one can hope for maybe 250k with these angles and some heavy advertising.
It really depends on who and how Ward beats before Kovalev. If he fights nobodies or has boring dirty fights with better opposition, then I doubt that the Kovalev fight will do more than 150k.
I doubt that it would be more if Ward doesn't demonstrate entertaining fights against decent real LHWs before the Kovalev fight.