[Subodh]

Hello Uday,

One org can hold max of 1000 permission set(1500 including Managed packages) and if we want, we can assign all permission sets to a single User.

You can run the following code snippet in developer Console to check by yourself:

integer count =1;
for(integer i = 1; i<=75;i++){
PermissionSet pr = new PermissionSet(Label='Case Permisson Set'+count,Name='Case_Permisson_Set'+count);
insert pr;
PermissionSetAssignment pm = new PermissionSetAssignment(AssigneeId='<User Id>',PermissionSetId=pr.id);
insert pm;
count++;
}

Hope this helps.!