Dotson drained five 3-pointers, while E.J. Singler and Carlos Emory provided 14 points each for the Ducks (28-8), who reached the Sweet 16 for the first time since 2007.
Arsalan Kazemi chipped in with eight points and 16 rebounds for Oregon, which had posted a one-sided win over fifth-seeded Oklahoma State in its Thursday opener.
The Ducks go on to face top overall seed Louisville March 29 at the Midwest Region semifinals in Indianapolis.
The fourth-seeded Billikens (28-7) got 18 points from Kwamain Mitchell and 16 from Dwayne Evans. They had topped New Mexico State 64-44 in the second round.