First, have you considered getting influx to do the work for you? See Write CSV data to InfluxDB | InfluxDB Cloud Documentation
If you don't want to do it that way then the first thing to do is to look at the help text for the batch node and see how the data must be formatted. When you have worked that out then come back and show us an example of the first few lines of the csv file and what you think the data you send to influx has to look like.
Having said that, however, unless you are regularly writing thousands of rows, I would not use the Batch node, but the normal Influx Out node, which can be given an array of values to write. See the last example for that node in the docs. If you set the csv to return an array then it should give you something quite close to what you want. Feed it into a debug node first to make sure it looks right.