We are still in the middle of the year. I see no reason why they can't finish the assembly of these aircraft in time.
The engines are a known quantity and they already make quite a lot of them with much same technology for the Su-35 also on production at same plant. You can see Su-35 in the foreground. Once available Su-35 orders are finished I expect the plant to switch fully to Su-57 production. Unless there is some sort of component shortage there is no reason to continue Su-35 production with Su-57 available.
Russia recently ordered about 40 more Su-35 to phase out aging Su-27. It'll be years for Su-35 production to finish.