Is it required to shut down a mature av fistula for surgery on the same side?

Usually yes: If there are 2 functioning av accesses on the same side, there is higher risk of access steal (not enough blood flow to the hand, producing hand pain and sometimes gangrene of the fingers). If the mature access is having problems (pseudo aneurysms, stenosis), most times we can repair it rather than sacrifice it to place another access.

No: Surgery " on the same side" means nothing to me. You would never close a fistula if it's functional and not necessary. In order to appropriately answer this question we would need to know what other surgery you were having performed.