This variable sets the total number of states that Octopus will use. This is normally not necessary since by default Octopus sets the number of states to the minimum necessary to hold the electrons present in the system. (This default behavior is obtained by setting TotalStates to 0).
If you want to add some unoccupied states, probably it is more convenient to use the variable
states/states_elec.F90 : 313
call parse_variable(namespace, 'TotalStates', 0, ntot)