Will magnet stick to silver plate?

Probably not.

You need a ferromagnetic material for a magnet to stick. There are basically three elements that are ferromagnetic: Cobalt [Co]; Nickel [Ni]; & Iron [Fe] (and some esoteric ones too). If the metal alloy that has been plated with silver to make the "silver plate" has enough of these then a magnet will stick, of these, only Nickel is commonly a component of alloys that are plated but often not in concentrations that are sufficient to make it obviously magnetic.