importing data from the text file into the layer--illustrator

Your question is very nonspecific, but here are the basic steps:  (1) read a file and (2) add the text to a layer (in this case, as area type).  (Replace "..." with the address to your file name.)

var address1 = "/C/Users/.../yourFileName.txt";
var file1 = new File(address1);
file1.open("e");
var contents1 = file1.read();
file1.close();
var doc1 = app.activeDocument;
var layer1 = doc1.layers.add();
var path1 = layer1.pathItems.rectangle(0, 0, doc1.width, doc1.height);
var text1 = activeDocument.textFrames.areaText(path1);
text1.contents = contents1;