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
],
                image_pull_secrets=self.image_pull_secrets,
                service_account_name=self.service_account_name,
                host_network=self.hostnetwork,
                security_context=self.security_context,
                dns_policy=self.dnspolicy,
                scheduler_name=self.schedulername,
                restart_policy='Never',
                priority_class_name=self.priority_class_name,
                volumes=self.volumes,
            ),
        )
        pod = PodGenerator.reconcile_pods(pod_template, pod)
        for secret in self.secrets:
            self.log.debug("Adding secret to task %s", self.task_id)
            pod = secret.attach_to_pod(pod)
        if self.do_xcom_push:
            self.log.debug("Adding xcom sidecar to task %s", self.task_id)
            pod = xcom_sidecar.add_xcom_sidecar(pod)
        return pod
    def create_new_pod_for_operator(self, labels, launcher) -> Tuple[State, k8s.V1Pod, Optional[str]]:
        """
        Creates a new pod and monitors for duration of task
        :param labels: labels used to track pod
        :param launcher: pod launcher that will manage launching and monitoring pods
        :return:
        """
        self.log.debug(
            "Adding KubernetesPodOperator labels to pod before launch for task %s", self.task_id
        )