Can an improvised torch be made to last for a prolonged period of time?
The key is whether or not he added some kind of fuel to the cloth. Without that, a flammable cloth would burn itself out very quickly. If he had kerosene or some other fuel to soak the cloth, then the cloth would act somewhat like a wick in an oil lamp (except that it would not be "wicking" fuel up from any fuel source) in that mostly the fuel would burn rather than the cloth.  

If he had a liquid fuel source, even a non-flammable cloth like his clothing would have been made of would have sufficed. In fact, he probably wouldn't have had to keep adding cloth in that case, but he would have had to add more fuel periodically.  

So, the bottom line answer is: Without a liquid fuel source to soak the cloth, no chance. With a liquid fuel source to soak the cloth, no problem.