Yes — Drew Lock is confirmed to start for the Seahawks in Week 2 against the Cardinals. Sam Darnold suffered a soft-tissue glute injury in the first quarter of Week 1 and has been ruled out. The Seahawks aren't placing him on IR, so he could return in roughly 4 weeks, but Lock gets the nod this week (from the Drew Lock page and Sam Darnold page).
Lock looked sharp off the bench in Week 1 — 16/22, 113.3 passer rating, and a 45-yard TD to JSN to upset the Patriots. That said, he's ranked QB27 for Week 2 — Seattle's run-heavy offense limits his fantasy ceiling, so he's a game-flow-dependent streamer at best.
On Mayo Media Network, they noted the flipside: "If we get the Drew Lock that played against New England, I think Seattle's in real trouble for these four to six weeks" — pointing to concerns about whether he can sustain that efficiency. Worth a monitor, not a must-add in most leagues.