I think people are confused with the word theory.
The definition of theory.
According to the Oxford Dictionary, theory can be understood in two ways.
Theory, Sense 1: A scheme or system of ideas or statements held as an explanation or account of a group of facts or phenomena; a hypothesis that has been confirmed or established by observation or experiment, and is propounded or accepted as accounting for the known facts; a statement of what are held to be the general laws, principles, or causes of something known or observed. Theory, Sense 2: A hypothesis proposed as an explanation; hence, a mere hypothesis, speculation, conjecture; an idea or set of ideas about something; an individual view or notion.
You seem to use theory in the second sense but science or Biology uses it in a first sense.
The first definition of theory makes evolution theory to be a fact just a Heliocentric is a theory.
It's in this sense evolution theory is a fact.
Evolution theory can be proved by modern science and the evidences are so overwhelmingly compelling.