Like anything else it takes money, experience, and patience. If you need to ask then chances are you can't.
A franchise store of that caliber usually requires 100k or more just to shake their hand (no not literally but you need have capital to get the business going and keep it running), a solid background with either KFC or running any other fast food establishment (it's their name you're taking charge of and failure or success reflects on them). Depending on the location you will either buy another store or will need to have your own built which YOU PAY FOR (only a million + dollar though) and it has to be in an assigned territory.
In many cases you may have to get on a waiting list that could take years before you get your store. When you finally do then you have to agree that you will buy every paper product, advertising material such as posters, sugar packets, cups...anything with the KFC logo on it plus royalty fees (a percentage of everything you sell.
They're lucrative if you know what you're doing because these stores struggle and if not ran properly can easily go under. One of the biggest problems fast food places deal with is all the unwanted traffic they get from the 99 cent menu customers that bring in little or no profit.