The Austrians failed to do this in 1761 when the Russians were helping them, so why would they have been able to do so with less men and less money than before?
Friedrich actually controlled more troops in Silesia than did the Austrians in 1762 even without Chernyshev's Russian army corps, and the Russians barely participated in the campaign before being ordered out again by Yekaterina. The Battle of Burkersdorf and the siege and capture of Schweidnitz, which are what effectively turned the tide in Silesia, were accomplished solely with Prussian troops. Heinrich's offensive against the Imperial army in Saxony that fall did not even require reinforcements from Silesia, and the victory he gained at Freiberg permitted the Freikorps to attack Thuringian territories and further hasten the end of the war.
Austria could not have sustained the war into 1763 arguably even with Russian support. Zinzendorf, the auditor-general, was convinced that the drain of further war would lead to state bankruptcy. It is probable that the war would have concluded with a peace of exhaustion anyway.
Friedrich actually controlled more troops in Silesia than did the Austrians in 1762 even without Chernyshev's Russian army corps, and the Russians barely participated in the campaign before being ordered out again by Yekaterina. The Battle of Burkersdorf and the siege and capture of Schweidnitz, which are what effectively turned the tide in Silesia, were accomplished solely with Prussian troops. Heinrich's offensive against the Imperial army in Saxony that fall did not even require reinforcements from Silesia, and the victory he gained at Freiberg permitted the Freikorps to attack Thuringian territories and further hasten the end of the war.
Austria could not have sustained the war into 1763 arguably even with Russian support. Zinzendorf, the auditor-general, was convinced that the drain of further war would lead to state bankruptcy. It is probable that the war would have concluded with a peace of exhaustion anyway.