The two cases are completely different- as you've likely noticed. The creation of the State of Franklin was something of a comedy of errors.

The Continental Congress had, during the Revolutionary War, drawn up the Articles of Confederation - a very brief document- that stated that colonies would be admitted into the United States by the votes of nine states. But a few years later Congress also stated that Virginia, North Carolina and Georgia would cede territory to create new states. Some Virginian settlers and other land speculators were led to believe that North Carolina was going to cede western territory for a new state, and started to set one up. But of course a number of well-connected land speculators in North Carolina had already been granted a lot of the Tennessee territory, and so when the Franklinites tried to get admitted as a new state, NC was against it. The first vote in the Congress in 1785 failed to get the necessary nine states ( VA and GA were opposed, SC was split, North Carolina could not vote). The matter was finally brought to the Constitutional Convention , in 1787, when it was decided that a new state could not be created from the territory of an existing state without the permission of that state.

Georgia and Virginia blocked the admission of Franklin in 1785 for obvious reasons- they wanted control over their own western claims -to sell to their own land speculators. It is hard to imagine them voting another way. Even before the War there had been a significant east-west divide in the 13 Colonies, and especially in North Carolina. Political power was firmly held by landed elites in the east, and they were seldom interested in sharing power or working for the interest of western settlers.

Someone might have a deeper knowledge of the East Tennessee Convention during the Civil War, but the possibility for a state in east Tennessee also seems pretty small. While the Wheeling Assembly in western Virginia was very soon able to claim to be the legitimate government, the admission of WV as a new state in 1864 took a lot of time and trouble- the Confederate voters of eastern VA may not have voted- or been able to vote- to keep WV from splitting, but few could doubt that they were against it. And even in the case of WV, the debate over emancipation threatened to stop the process. By the time of the East Tennessee Convention, the Emancipation Proclamation had put the issue at the front of any such discussions, and the Convention was much more rancorous from the start, with Samuel Brownlow firmly arguing for emancipation but a large number of Democrats firmly against. There was also the fact that while West Virginia was soon under federal control ( with any hopes of that changing ended with the last Confederate defeat at Droop Mountain in Nov. 1863,) East Tennessee would see a much longer conflict, and the proponents of a new state would actually see much more war in their own communities. The Battle of Nashville wouldn't settle the matter until Dec. 1864.

So, if you want to hypothesize East TN becoming a state, you'll have to overcome either the resistance of VA, GA and SC in the 1785 vote in Congress, or overcome the divisive issue of emancipation in 1861 and assume much greater Union control in east Tennessee.