How do I view operators in a Notify Operator task in a Maintenance Plan?
Two ways come to mind, there may be more. I prefer the second but that's just my opinion

Import-Module SQLPS -DisableNameChecking
Get-ChildItem SQLSERVER:\SQL\ServerNameHere\DEFAULT\jobserver\Jobs |Select Name, OperatorToEmail


The first line below loads the 2012 assembly since that's the version I'm running on my laptop, adjust to suit your needs.

Add-Type -AssemblyName "Microsoft.SqlServer.Smo, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91"
$srvObject = new-object -TypeName Microsoft.SqlServer.Management.Smo.Server -ArgumentList 'ServerNameHere'
$srvObject.JobServer.Jobs| Select Name, OperatorToEmail