Yes, a facedown monster can be Tributed in order to Tribute Summon a monster.

But as usual, you can only Tribute Summon if you have not already done your "Normal Summon or Set" for the turn.

To perform the Tribute Summon, during your Main Phase I or II, send the monster(s) you are Tributing to the Graveyard. If the monsters were face-down, they do not flip when they are sent to the Graveyard. Then place the monster you are summoning in a Monster Card Zone in face-up Attack Position or face-down Defense Position (this counts as a Set and not a Summon, but it still counts as your "1 Normal Summon or Set").

However, you cannot do this if either player has a "Mask of Restrict" active.