There are an infinite number of excited states.
The Bohr Theory assigns quantum numbers (n = 1, 2, 3 … ∞) to each energy level. n = 1 is the lowest level (the ground state).
An electron is in an excited state whenever it is at a higher level than the lowest level possible.
The energy difference between adjacent energy levels gets smaller as n increases. For example, the difference in energy between n = 6 and n = ∞ is small.
There is also a largest energy that each electron can have and still be part of its atom. Beyond that energy, the electron is no longer bound to the atom — the atom ionizes.