Is the Portal (videogame) series based on I Have no Mouth and I Must Scream?

Portal is actually based off an earlier freeware video game called Narbacular Drop (in fact, Valve hired the people who made the original game to come work on Portal). While the developers have cited similarities between GLaDOS and 2001: A Space Odyssey's HAL 9000, no such comparison has ever been made by them to I Have No Mouth, and I Must Scream.