The question of how much pressure a five-kilowatt generator requires requires more context and detail. Generators generally do not generate electricity by pressure, but generate mechanical work by burning fuel or converting other energy sources. Pressure often plays an important role in the combustion chamber of a generator or turbine.
If you are referring to an internal combustion engine generator, some key parameters such as fuel injection pressure and combustion chamber pressure will affect the generator's performance. Different models of generator equipment will have different parameters and design requirements, so there is no simple answer as to what pressure will meet the needs of a five kilowatt generator.
On the other hand, if you are referring to a turbogenerator, what must be taken into account is the principle ofe operation and parameters of the turbine, such as rotation speed and inlet pressure. Turbine performance is directly related to inlet pressure, and generator output power is directly derived from pressure rather than pressure.
In summary, more context and detail are needed to answer the question of what pressure a five kilowatt generator requires.