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The interplay between band topology and magnetic order plays a key role in new quantum states of matter. MnBi₂Te₄, a crystalline topological van der Waals magnet, has recently emerged as an exciting platform for exploring Chern insulator physics. Its layered antiferromagnetic ground state was predicted to enable even-odd layer-number dependent topological states, while tunability of spin states via external magnetic field offers an interesting venue for observation of topological phase transitions. In this work by combination of magnetic circular dichroism, transport, and microwave impedance measurements (MIM) we investigate connection between bulk electronic structure, topological order, and magnetic states in thin flakes of MnBi₂Te₄. We establish one to one correspondence between spin state and Chern number in this material and observe band crossing, which is closing and reopening of bulk bandgap as a function of external magnetic field. Furthermore, we investigate Chern gap formation in MnBi₂Te₄ and its evolution as a function of temperature. Finally, we will discuss even-odd layer-number dependent effects on bulk electronic structure of MnBi₂Te₄ and Chern insulator state formation.