Overall, 5/8 of the Ukrainian population is listed as non-religious. Among the religious, the main split seems to be Orthodox/Kiev Patriarchate, 32.8%, versus Orthodox/Moscow Patriarchate, 29.4%. Greek Catholic = Uniate 14.1%. (From Wikipedia and World Almanac.)
The political split (map of election returns) correlates better with languages. Has anyone found a map specifically showing the pro-EU vs pro-Russian split? I had no luck with this a couple of months ago.