You can also directly execute gsutil command on your GCE VM (Most VM images have Cloud SDK preinstalled). For example:
gcloud compute ssh user@server --zone my_zone \
--command='gsutil cp path/to/my_file gs://MY_BUCKET'
Note that for this to work your service account associated with VM must have appropriate access scope to GCS. If you run
gcloud beta compute instances describe my_instance --zone my_zone \
--format="value(serviceAccounts.scopes)"
It will show list of scopes set for VM service account. Make sure you have https://www.googleapis.com/auth/cloud-platform or https://www.googleapis.com/auth/devstorage.full_control or https://www.googleapis.com/auth/devstorage.read_write. If not you can use
set-scopes beta command to reset them or go to console and edit VM in question.