In a 2-player game the difference between a win and a loss is always exactly your K-factor.
Example:
*) If your win probability is 0.8 and your K-factor is 20 then you get +0.2 * 20 = +4 points for a win and -0.8 * 20 = -16 points for a loss. A draw lies right in the middle with -0.3 * 20 = -6 points.
*) If your win probability is 0.1 and your K-factor is again 20 then you get +0.9 * 20 = +18 points for a win and -0.1 * 20 = -2 points for a loss and 0.4 * 20 = +8 points for a draw.
In a 4-player game there is an additional factor that dampens the K-factor. I never remember the formula but a 4-player game is not exactly equivalent to 3 separate games that you play. Otherwise a win/loss in a 10-player game would lead to extreme jumps in ELO. But this aspect introduces just a "K_4"-factor for a 4-player game that is equal to your K-factor multiplied by some 4-player-game constant which is smaller than 1.
But then you have the same effect as in the 2-player scenario. The difference between 1st and 2nd place is exactly your K_4-factor, same as difference between 2nd and 3rd, and 3rd and 4th place, respectively. Because as 1st place you beat #2,#3,#4 and as 2nd place you still beat #3,#4 but now you have a loss instead of a win against one player (see 2-player scenario).
Thus the difference between 1st and 4th place is always exactly 3 times your K_4-factor - independent of the ELO values around the table.