What you're looking for is to get the job id of the AWS Batch job that gets executed as one of the steps of the step function pipeline. However, you aren't able to get that because your webserver is trigerring the step function pipeline, not invoking the aws batch job directly.

The best solution for you is to generate a "job id" in your webserver before trigerring the step function. After triggerring the step function, store the "job id" and the step function's executionARN in your jobs table, and return the "job id" to the client. When the client needs to check the status of the job, they will use this "job id" and you will use this "job id" to look up the associated step function executionARN from your jobs table and use that to poll the step function status. You won't get the aws batch job's status; but that is irrelevant for your use case, since the client would just be interested in knowing entire process' status, meaning your step function pipeline succeeded or failed.