The midfielder struck a minute from time on Tuesday to add to Diego Godin's second-half opener as Atletico won 2-0 at Vicente Calderon.
The fixture came just three days after their goalless La Liga draw with Barcelona and Garcia believes that the cup win is proof of Atletico's strength-in-depth.
"We're still on the same path as before," he told AS.
"We've enough depth in the squad to battle in three competitions, which is what we are doing."
After their draw with Barca, Atletico sit level on points with the champions at the top of the table and will face Milan in the first leg of their UEFA Champions League last-16 clash next month.
With victory against Valencia keeping their treble hopes alive, Garcia was also pleased to see Atletico respond well from Saturday's "demanding" clash.
"It’s fair to say that (the Barcelona fixture) was a demanding game for us," he added.
"We have reached the level where we cannot lose any game and now, that's what makes other teams want to beat us. But physically, the team is still strong.
"Valencia are difficult opponents in spite of however they are doing in the league. In the end we prevailed and the result speaks for itself."
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