If a file is uploaded into the IPFS network, how is the content distributed? Is the content split and stored in the same node or distributed among the nodes in the network?
By default, the content never leaves the adding node unless the content is requested from someone else. The adding node just advertize to its peers via the DHT that it hosts this content and that it will serve it on-demand if the ask it for it.
The only case where data is “pushed” to other nodes, is when using IPFS Cluster, that handles automatic replication of content on collaborative nodes.