It sounds like you're very new to PWC's. First of all, ANYTHING that's been sitting any length of time will need the WHOLE fuel system gone through. Clean out gas tank, inspect fuel pickup, inspect/replace fuel lines, vacuum test fuel switch, and rebuild the carb. ***Failure to do this on a large 2 stroke WILL result in engine damage if you try to ride it.***
BUT....before you go through any of that, you need to do a compression test so you know if the motor is any good. If the compression is good.... Next, spray a bit of WD40 and a bit of carb cleaner in each plug hole, install spark plugs, crack the throttle open a hair, then crank it. It should light off and run for a second or 2.
Start with the basics and report back.