Save or no save?
 

Pitcher begins the 8th inning with his team leading, 12-7. He works the 8th and the 9th innings, and his team wins, 12-9. He is on the mound when the game ends. In the 8th, he worked out of a bases-loaded jam; in the 9th, he stranded two runners in scoring position.

Does this pitcher get a save, even though it was not a save situation when he entered the game?

No. Just because he worked himself into what would be a save situation does not mean he qualifies for a save. When he enters: his team must be ahead by 3 or fewer runs, OR the tying run must be on base, at bat, or on deck. If neither of those requirements are met, he must pitch 3 or more innings. Since he came in at the beginning of the 8th with a lead of 5, he does not qualify for a save.

He cannot create the save situation, now if he entered the game with bases loaded in 12-7 game that would be because the potential tying run is on deck.

Save
 

I thought if the tying run can come to the plate without hits/walks/etc, that the pitcher gets the save.

So 12-7 means the 5th batter could tie the game and since he faced 6 minimum, he gets the save.

Unless he pitches 3 innings, all that matters is the situation when he enters. Since he started in the 8th (only 2 IP), with a 5 run lead (more than 3 R lead), and the tying run not on base, at bat, or on deck (would be the fifth hitter of the inning), he can't qualify. If he had come in with the bases loaded and leading by 5, he could qualify since the tying run would be on deck when he entered.

He entered the game with nobody on (is how I read the original post) if he inherited the bases loaded, like the reliever before him loaded the bases, then yes he would of got the save, but you cant pitch your way into a save situation. Like if your up 4 give up a 2 run bomb (charged to you)and team wins by 2, you dont get the save because all of a sudden was a save situation.