Young Einstein had a lot of people he respected, but arguably the biggest intellectual influence on him (who he didn't know personally) was Ernst Mach, the physicist whose name we associate with shock waves, but Einstein would have thought of as a philosopher of physics. Mach put out the radical idea (then and now) that the only entity that physicists should consider are things that can be directly measured (this is called Machian positivism). This might sound straightforward but there are plenty of things in physics that we cannot directly interact with, much less measure, and many concepts that we don't think of as being only about their measurement. The influence can be seen in Einstein's shifting sense of "time" and "six" as universal properties to something that only exists in the framework of measurement (hence all of the discussions about how my clock or your clock will measure things differently depending on our speed and velocity and all that). This "kinematical" approach is especially evidenced in Einstein's famous 1905 papers, and is extremely Machian, even in the papers when he tries to come up with arguments for things that cannot be measured within this framework (his paper on Brownian motion, for example, is an argument in favor of molecules and atoms as physical entities — not something that needed to be proven in 1905 — that tries to show how you can use inferences to produce an equivalent alternative to direct measurement; Mach wasn't convinced, but it's an interesting motivation by itself).

Other than that, the other luminary who factors into pre-famous Einstein's life in a major way is Henri Poincaré. I think saying Einstein "looked up to him" is not wrong but their relationship was very different than with Mach. Einstein and Poincaré were interested in very similar problems but their philosophical foundations and goals were extremely different. In many ways Poincaré was the "old guard" that Einstein was trying to supplant. They never had any kind of actual relationship between them, even after Einstein got famous; Poincaré basically ignored him. But his work, and the problems he was interested in (like the relativity of simultaneity) motivate a lot of Einstein's early work, even though they ended up with very different conclusions about it.

On these two particular influences, see esp. Peter Galison, Einstein's Clocks, Poincaré's Maps (which as the title implies is about Einstein and Poincaré in particular), as well as the chapter on Einstein and Mach in Gerald Holton's Thematic Origins of Scientific Thought.