Did Stan lee steal characters from jack Kirby and Steve ditko?

No, he didn't.

1. All characters created at Marvel Comics until the early 1980s- including those created by Stan Lee- were owned completely by Marvel, NOT Stan Lee, NOT Jack Kirby, NOT Steve Ditko. None of them get any $$ from "ownership" of the characters, so what was there to 'steal'?

2. Steve Ditko is the CO-creator of Spider-Man, but Stan Lee came up with the concept. Stan gave Ditko the assignment to come up with the look for a new character to be called Spider-Man, a shy teen who lived with his elderly aunt and uncle. Ditko came up with the costume and web-shooters. Ditko himself refers to Spider-Man as "our [Stan Lee & Steve Ditko's] creation."

Stan Lee has given credit to Ditko, Kirby and others as the artists who created the visual looks of the characters they worked on and, where applicable, as story plotters/co-plotters since the beginning. Monetary renumeration was not in Stan's jurisdiction- he was Editor-in -Chief, not owner of the comopany, and he had to abide by corporate policy like everyone else, whether he agreed with it or not.