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
from kubernetes.client import CoreV1Api, models as k8s
try:
    import airflow.utils.yaml as yaml
except ImportError:
    import yaml
from airflow.exceptions import AirflowException
from airflow.kubernetes import kube_client, pod_generator
from airflow.kubernetes.pod_generator import PodGenerator
from airflow.kubernetes.secret import Secret
from airflow.models import BaseOperator
from airflow.providers.cncf.kubernetes.backcompat.backwards_compat_converters import (
    convert_affinity,
    convert_configmap,
    convert_env_vars,
    convert_image_pull_secrets,
    convert_pod_runtime_info_env,
    convert_port,
    convert_resources,
    convert_toleration,
    convert_volume,
    convert_volume_mount,
)
from airflow.providers.cncf.kubernetes.backcompat.pod_runtime_info_env import PodRuntimeInfoEnv
from airflow.providers.cncf.kubernetes.utils import pod_launcher, xcom_sidecar
from airflow.utils.helpers import validate_key
from airflow.utils.state import State
from airflow.version import version as airflow_version
if TYPE_CHECKING:
    import jinja2
class KubernetesPodOperator(BaseOperator):