To answer your second question, say creative tourism is not a theory, then what is "the theory" you are referring to?
Back to the first question. In science, a theory is "a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses."
Is creative tourism a theory then? Can it "be repeatedly tested and verified in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results"?
In tourism services, as in many other quickly developing fields in recent years, the key issue is innovation, creativity, offerings, marketing, etc. In recent years, the importance of creative implementation of sustainable development principles in tourist services has grown. However, at present (April 2020), unfortunately, in many countries due to the development of the SARS-CoV-2 coronavirus pandemic causing Covid-19 disease, tourism development has stopped, recession. The tourist market has decreased many times. Therefore, nowadays tourism companies must also be creative and innovative in order to survive the current difficult period of economic downturn.
I heard sustainability approaches or stakeholders theory for supporting the study...but never heard about the creative tourism theory.. Creativity can be a factor/ can be a dimension for sustainable tourism. However, creativity can be a dimension and practice only..