KubernetesPodOperator  pod_template_file content doesn't support jinja airflow template variables. pod_template_file  is part of templated_fields list. 
https://github.com/apache/airflow/blob/master/airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py#L165

template_fields: Iterable[str] = (        'image',        'cmds',        'arguments',        'env_vars',        'labels',        'config_file',        'pod_template_file',    )

But pod_template_file content is not supporting template variables. pod_template_file can be implemented the way SparkKubernetesOperator implemented using template_ext

https://github.com/apache/airflow/blob/master/airflow/providers/cncf/kubernetes/operators/spark_kubernetes.py#L46
 template_ext = ('yaml', 'yml', 'json')
airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py
"""
    Execute a task in a Kubernetes Pod
    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:KubernetesPodOperator`
    .. note::
        If you use `Google Kubernetes Engine <https://cloud.google.com/kubernetes-engine/>`__
        and Airflow is not running in the same cluster, consider using
        :class:`~airflow.providers.google.cloud.operators.kubernetes_engine.GKEStartPodOperator`, which
        simplifies the authorization process.
    :param namespace: the namespace to run within kubernetes.
    :type namespace: str
    :param image: Docker image you wish to launch. Defaults to hub.docker.com,
        but fully qualified URLS will point to custom repositories. (templated)
    :type image: str
    :param name: name of the pod in which the task will run, will be used (plus a random
        suffix) to generate a pod id (DNS-1123 subdomain, containing only [a-z0-9.-]).
    :type name: str
    :param cmds: entrypoint of the container. (templated)
        The docker images's entrypoint is used if this is not provided.
    :type cmds: list[str]
    :param arguments: arguments of the entrypoint. (templated)
        The docker image's CMD is used if this is not provided.
    :type arguments: list[str]
    :param ports: ports for launched pod.