Some 800,000 Jews, appx 90% of the Jewish population, were killed in Belarus during the Holocaust.As of 2005,there were some 50,000 Jews in all ofBelarus.In Poland there were appx 5,000 left after WW2. ____________________________________________
The surnames you listed do not strike me as Jewish surnames. They are very likely Russian Orthodox, Christian.
A surname like Fedorov is rooted in Greek given name, Theodor, meaning GIFT OF GOD.There is no TH sound within Cyrillic Alphabet.TH =F sound.
I checked both Brest and Grodno for the surnames and found, with the exception of Miziuk, all fairly common to both towns.Bare in mind that many villagers have migratedto the larger towns and cities for economic reasons.
Closer transliteration (sounds like) of surnames you are researching:
Denisiuk = Denysiuk Miziuk = Miziuk (rarest of all the surnames on your list - just several show up in Grodno) Fedorov = Fedorov Samuiljonok ??? = could be Samojlenko, Samojlyk, Samojlo, Samojlov, Samollovych, Samojlol (Samojlenko is the most common, although most show up in Grodno and a few in Brest).