Alas, not true. Vendyl Jones has claimed this, but both Spielberg and Lucas deny it. The script was in fact written two years before Jones made his claims, and Lucas maintains that the first name of the character is, in fact, named after a dog, after all. :)

http://en.wikipedia.org/wiki/Vendyl_Jones
http://theindyexperience.com/tie_lite/august_2005.shtml#0000669/
http://www.watchman.org/reltop/filmdig.htm