The idea that everything could be predicted like a machine is more closely associated with René Descartes. Descartes was a philosopher and mathematician who applied mechanistic explanations to the natural world, positing that physical phenomena could be understood in terms of mathematical laws and mechanical principles.
Johannes Kepler, on the other hand, is best known for his laws of planetary motion, which described the orbits of planets around the sun. While he did believe in a mathematical universe, his work was more focused on the specific laws governing celestial bodies rather than a broader mechanistic view of all phenomena like Descartes.
So, the answer is René Descartes.