  Fe$_3$GaTe$_2$, a recently discovered van der Waals ferromagnet, demonstrates
intrinsic ferromagnetism above room temperature, necessitating a comprehensive
investigation of the microscopic origins of its high Curie temperature
($\textit{T}$$_C$). In this study, we reveal the electronic structure of
Fe$_3$GaTe$_2$ in its ferromagnetic ground state using angle-resolved
photoemission spectroscopy and density functional theory calculations. Our
results establish a consistent correspondence between the measured band
structure and theoretical calculations, underscoring the significant
contributions of the Heisenberg exchange interaction ($\textit{J}$$_{ex}$) and
magnetic anisotropy energy to the development of the high-$\textit{T}$$_C$
ferromagnetic ordering in Fe$_3$GaTe$_2$. Intriguingly, we observe substantial
modifications to these crucial driving factors through doping, which we
attribute to alterations in multiple spin-splitting bands near the Fermi level.
These findings provide valuable insights into the underlying electronic
structure and its correlation with the emergence of high-$\textit{T}$$_C$
ferromagnetic ordering in Fe$_3$GaTe$_2$.
