You it would impact public opinion if the public were Americans. Not in Russia though because Putin is a dictator and has been in power for 18 years and doesn’t care what Russians think of him.

That only works to a limited extent. When you stretch your economy with a war and actively disregard the citizenry, don’t be surprised when you end up like Tsar Nicholas, who also enjoyed absolute power until he didn’t.

Public opinion refers to the opinion of the general population. Whether or not Putin cares about it or not doesn’t stop it from existing.