More than cavalry. Early approached Washington D.C. with an army of nearly 10,000 men.
While Gettysburg was the largest battle of the war. It’s main accomplishment was break the offensive power of the Army of Northern Virginia. Lee lost about one third of his army as casualties. For the rest of the War, the ANV was pretty much limited to going wherever the Army of the Potomac wanted to go.
Whether it was the turning point of the war is debatable. Some think McClellan’s drawn battle at Antietam had more impact on the outcome of the war than Gettysburg. The reason is that it was just enough of a win for Lincoln to issue the Emancipation Proclamation. That event made European intervention, on the side of the Confederacy, very unlikely. Without direct European intervention, the prospect of the Confederacy winning the war declined drastically.
Interestingly, the high losses at Antietam were what prompted Lee to invade western and southern Pennsylvania the following year as he knew the south couldn't win a protracted peace. June 1863 was an interesting month in western and southern Pennsylvania history. Lee's army burned military targets such as the steel works outside of Pittsburgh, but generally behaved in civil fashion otherwise. There is one episode where he sent a cavalry unit commander back to a storekeeper to apologize and pay for headgear they had rather forcibly "traded" to acquire. Quite the contrast to Sherman's army's behavior on their march from Atlanta to Savannah.