Galileo Galilei
Copernicus (16C); supported later by Galileo using observations aided by the newly-developed telescope.
Galileo Galilei . He only helped support the theory through his observations , he didn't invent the model, Copernicus did.
Aristotle said the earth was in the center. Ptolemy supported Aristotle and added to it. Copernicus said the sun was in the middle. Galileo also said the sun was in the center and added to Copernicus.
Galileo
I suspect the answer you're looking for is Galileo Galilei. It just has two problems: Galileo didn't "invent the telescope", nor did he "develop a heliocentric view of the universe." The telescope was invented in the Netherlands; Galileo simply improved on it and was probably the first to apply it to astronomical observations instead of just looking for distant ships. Also, Copernicus is (properly) credited with the heliocentric view; Galileo's observations supported this, but he didn't come up with it.
Copernicus created the mathematical theory to prove that the Sun, not the Earth, was the centre of our solar system. Galilei provided the calculations and observations to prove Copernicus' theory.
heliocentric theory
Copernicus developed the theory, Galileo supported it with his observations.
the Earth revolves around the Sun, which challenged the geocentric model of the universe. His discoveries also supported the heliocentric model proposed by Copernicus. Galileo's observations with the telescope provided evidence for this idea.
The discovery did not support Copernicus's theory directly but it raised doubts about the ancient theory of Ptolemy that said that all objects in the sky are in orbit round the Earth. Galileo was an aggressive supporter of Copernicus's theory but eventually it was Kepler's theory that became accepted and is still used today. Both Copernicus and Kepler placed the Sun at the centre but Kepler's elliptical orbits are supported by the later theory of dynamics.
A theory is the result of many, many tests and observations.
Because it was supported by observations.