G Major or e minor. The sharp would be F sharp.
A key signature with one sharp (F#) would be either G major or E minor.
Four key signatures have G sharp and E sharp in them: F sharp Major, D sharp minor, C sharp Major and A sharp minor.
An E natural minor scale is written with a one-sharp key signature, so you just write out the scale in semibreves and add an additional D sharp for the harmonic minor, and two additional sharps to the sixth and seventh degrees when ascending in the melodic minor (C sharp and D sharp). You lower the sharps and revert back to the natural minor when you descend through the scale.
There is only one sharp in G minor: the F# in the harmonic and melodic minors. The key signature for G minor is two flats, so the answer to your question is pretty much zero. Its leading tone, however, is F-sharp, always written with an accidental, so I suppose one could consider that there is one sharp in G minor, although not in the key signature. Please also see the related link about the G minor scale.
The parallel minor of F-sharp major is F-sharp minor. A parallel minor key is the one with the same tonic note.
The natural minor scale with the most sharp notes is E natural minor, which has one sharp note (F#).
The key of E minor has one sharp: F sharp. It is the relative minor of G Major.
G Major or e minor. The sharp would be F sharp.
One sharp could be G major or E minor.
E minor contains one sharp: F.
D sharp minor
A key signature with one sharp (F#) would be either G major or E minor.
In A harmonic minor, there is just one sharp (G sharp).
Fx (f double sharp) minor.
The natural minor has 5 and the harmonic minor has 4 and a double sharp.
Four key signatures have G sharp and E sharp in them: F sharp Major, D sharp minor, C sharp Major and A sharp minor.