We don't have any option to stream from s3 for now.
This does not seem very hard to implement. You can read the data from S3 and pass it to DataStreamer. Pay attention to CacheDataStreamerExample and examples under org.apache.ignite.examples.streaming package.
I still think we should have automatic integration, will create a Jira and post it here. If you end up doing it, please consider contributing it to Ignite, so the rest of the community could benefit from it.