X/Y time signature (but I don't think
X matters here). What would be the duration of a
n-tuplet (of 8th, 16th and 32nd notes), depending on
A time signature does not affect the duration of any tuple.
An 8th note triplet will always take up 1/3 of a quarter note
A 16th note triplet will always take up 1/3 of an 8th note
A 32nd note triplet will always take up 1/3 of a 16th note
An 8th note duplet will always take up 1/2 of a dotted quarter note
A 16th note duplet will always take up 1/2 of a dotted 8th note
A 32nd note duplet will always take up 1/2 of a dotted 16th note
This is regardless of meter. You are much more likely to come across triplets in an simple meter and duplets in a compound meter, but regardless the durations are the same.
This pdf is good resource for the basics of how tuples work.
Most tuplets are not affected by the time signature. However, two duplet eighths in 3/8 will cover 3/8, two duplet eighths in 5/16 will cover 5/16. A septole eighth in 4/4 will likely cover a whole measure unless the composer is from the school that n-toles may only be shorter than regular notes (but then how to explain duplets?).
In cases where you have to fear to be misunderstood, it may be better to write the note ratio out, so write either 7:4 or 7:8 instead of just 7.