Depends. Lee had plans to divide the army into three corps long before Jackson died, so it's impossible to say that it would have been Jackson coming in from the North. Ewell could still have approached from that direction and Jackson could have been coming in from the west, as Hill did. Or it could have been Longstreet coming in from the west and Jackson not arriving until day 2. You never know.
If Jackson I had lived, the ANV would probably have been still had just 2 corps. Ewell was sent to Pennsylvania first to see if there were enough supplies to sustain the army. Once that was determined, he was sent to Harrisburg. Would Lee have still done that? If so, would the faster moving Jackson had reached the city before the Union army crossed the Potomac?