Pipe chaining/splitting doesn’t work like you’re trying to do here, sending the first to two different subsequent steps:

sourceFileStream.pipe(gzip).pipe(response);

However, you can pipe the same readable stream into two writeable streams, eg:

var fs = require('fs');

var source = fs.createReadStream('source.txt');
var dest1 = fs.createWriteStream('dest1.txt');
var dest2 = fs.createWriteStream('dest2.txt');

source.pipe(dest1);
source.pipe(dest2);