Forward Silva, signed from Porto, netted from the penalty spot with 15 minutes left of the match in Catania, having earlier had a goal ruled out by a VAR review and been denied by some inspired goalkeeping from Dani Gimenez.
His intervention from 12 yards came eight minutes after Betis substitute Fabian had scored with a magnificent strike.
But Betis won it in the last minute when VAR again worked in their favour, penalising Hakan Calhanoglu for a handball that allowed substitute Antonio Sanabria to score from the spot.
