Sorry, Slornie, but I disagree.
To be honest, there is no question here. THE EMPIRE WOULD REIGN SUPREME!
The fact that the rebel Alliance attacked, would even help the empire in this case. The threat from within would drive the citizens of the empire into paranoia, and even more would enlist into the military. Don't forget that History is written by the victor, so if the empire wins, then the rebels would be written off as radicals, and the empire would be able to tighten their grip further in every system, in the name of eradicating the last members of these radical groups. Even after the last rebels would be captured, it wouldn't stop. Propaganda holonet transmissions would tell about "newly captured rebels", even if this would be nothing but a lie to further the empire's goals, and they could also use this as a method to find people whom WOULD rebel in the future.
Also don't forget that war usually brings technological advancements, which are being implemented in other areas in peacetime. Since that peace never came with the NR, we don't know how much it would have improved the life of the average citizens, but we know that it would most possibly doubled the imperial economy
From one side, the clearly rebeled worlds like Mon Calamari would have paid war repentions to the Empire, and their skilled shipbuilders would have been enslaved. The empire would also be able to get their hands on the last remaining A-, B- and X-wings too, and reverse-engineering them they could produce even more advanced fighters.
The Defender was planned to be regularized, just with the Emeror's death and the empire's fracturing, it became impossible.
With the rebels gone, however it would be not just possible, but probable.
With the TIE fighters being replaced by Defenders, and the Interceptors by the combined Rebel-Imperial technology, the Empire would have the same quality fighters as the rebels, and now for a very low price, as Companies would have nothing else, but accept the empire's will. This would come from Incom's defection, and their most possible live execution on every holonet-network.
With the Deathstar II finished, I believe the empire would also learn something from this attack, just like at Yavin. The deathstar shield worked marvelously. I believe that the Empire would also start the construction of the new Deathstar III keeping this in mind, it being equipped with shields and an even more advanced reactor to compensate for the shield's energy drain.
The war with the rebels would also lead the even faster expansion of the Imperial fleet, so the stuff you have written in the beggining would (I think) be even a conservative estimate, and the numbers would probbably be WAY HIGHER.
I think the most prominent advancements in the average citizens' life would be the advancements in the Droids (prominent by Darktrooper projects) and medications at the beggining. Then better trading, as even more trade routes would have been set up, and even more planets being found. Also, this would allow the even faster mapping of the unknown region and maybe even in the Wild Space.
The biggest advancements, however were in the targeting computers. I think the fact that the DS I was only able to target placets, while the DS II was able to target the size of a fishtank with it's superlaser is an astounding advancement. An advancement which would most possibly be used to equip all the ships with better targetting computers, therefore being even more effective.
The Eclipse and Sovereign classes also proved that a superlaser can be mounted on ships.
I think that most SSD classes would be built, or if already built then modify to house a superlaser.
Remember what happened after the clone wars. The empire could manage a rapid expansion, the state was stabilized from being in the brink of collapse(I know it transitioned from republic to empire, but both financially and combat power wise was the same strength), and solidified it's hold on the known galaxy. This would repeat itself, just with an even better rate. The empire was far from collapsing at Endor. If Palpatine would have survived endor, the empire could have afforded to wage war against the rebels for a long time. It was only the chaos after his death that brought the empire to it's knees.
So basically, yes. It is pretty clear that the empire would have won.