Most of the people in East, South and Central Ukraine speak Russian and learned Ukrainian in schools. It's also most populous part. In the West majority are anti-Russian and sympathetic to WW2 ideologies of then Nazi Ukrainian nationalists. That's why after far right hijacked Maidan protests they had to outlaw Russian leaning parties, politicians, broadcasters, etc ban use of Russian language in schools and offical capacity, etc. Although most Ukrainians were pro EU and wanted to join EU they were also pro Russian as well.
It's hard to say what the feelings of people after 7 years of conflict are now but it's guaranteed that large chunk of population in East, South, Central Ukraine would welcome Russians as liberators and large chunk wouldn't resist Russian occupation.
