In the last chapter we discovered that Kaido know about Joy Boy, soo probably he knew at least something about the will of D., probably from his times with Rocks, as Rocks seems to have been after the mysteries of the world, and probably even have discovered about the existencia of Imu, thats why he want to become the New King of the world.
For what seems, the Will of D. is not completely know by anyone besides Roger Pirates, WB and the high ups of the WG, but some people in the world at least seems to knew that there's something with the D. people and have some info on this.