I'v installed the google cloud shell, and i want to know if is there any command to initialize it from windows powershell.
TL;DR: No by using Powershell but yes using normal CMD.
You can use command gcloud alpha cloud-shell ssh to open a new session from Powershell to your cloud shell instance using SDK Shell (CMD). Before running the command, be sure that you have installed Cloud SDK for windows so you will be able to ssh to your Cloud Shell instance.
Regarding Powershell, unfortunatelly based on Cloud Tools for PowerShell cmdlet reference accessing (ssh) the Cloud Shell using Powershell is not yet supported. You can create a Feature Request in Google Cloud Issue Tracker to request this feature to be added to Powershell.