Fermatas do not have a specific length. You would just hold the note longer than the value for effect typically at the discretion of the performer or conductor based on what kind of effect you want. 

For this specific piece, the tempo is pretty fast so any piano should be able to sustain it easily and the piece is well known enough that you can listen to how long others hold the fermata to get an idea of how long it is held. I've included one version of this song for you to listen to. 

https://www.youtube.com/watch?v=KwNonij12tQ