Andy Chalk said:
Here's a slightly higher-res version of the comparison pic, which is a little easier to make out:
The style is similar, but the ridges are identical. Definite lift.
So? A video game sequel makes their poster a sendup to The Empire Strikes Back. It's a visual gag.
American copyright law even makes allowances for lifting pieces from someone else's work, with factors like whether the use was transformative, whether the portion copied was large or substantial, the effect of the use on the potential market. I'm not a lawyer, but I don't think copying the original poster could possibly hurt the original poster's value in any way, shape, or form. I'm fairly certain that Gearbox could go to court and win, and it would be a bitter waste of everyone's time.