Running a git pull with ssh remote command

[Xavi]

branches: master: 
- step: *PHPCS 
- step: name: Deploy to Demo 
deployment: demo 
# trigger: manual # Uncomment to make this a manual deployment. 
script: 
- echo "Deploying to demo environment" 
- apt-get update -y 
- apt-get install -y ssh 
- ssh -A -T $ssh_user@$ssh_host "git --git-dir=$path/.git --work-tree=$path pull origin master"

I have this in my pipelines file. the ssh logs in to the remote server. I have tested a similar command locally with the save value the variables have and it works as expected. In the pipelines though I keep getting an access denied public key error,

Permission denied (publickey).fatal: Could not read from remote repository.Please make sure you have the correct access rightsand the repository exists.

 any ideas, would be greatly appreciated.