Eumaeus acts as a father figure to Telemachus during Odysseus' absence. He stays loyal to Odysseus, and when he meets Odysseus as a beggar, allows him to stay at his house. Further he tells Odysseus...
Yes, he is because he has a relationship with him as a friend before he leaves Ithaca. However, later on it may not seem so, because Eumaeus sees Odysseus after he has been transfigured by Athena.