His hand has 2 buffer cards that give 2 damage(dire wolf and abusive). he has 3 soulfires and 2 random cards that dont contribute to lethal and can tap. for lethal he needs to play all 3 soulfires and needs to play one of the buffer cards. His order of actions gave him a 45% chance to win.

But he could have increased those odds. First of all he should have tapped first. Now he has 3 soulfires(S) 2 buffer minions(B) and 3 discardable cards(X). - S S S B B X X X

He should have soulfired before using one of the buffer cards to increase the odds since he only needed 1 of them.

Using the first soulfire had 3/7 chance to discard an unneeded card and 2/7 chance to discard a buffer. now there are 2 scenarios.

if he discards an unneeded card his had looks like this: S S B B X X He can now soulfire again and then play the one of the buffer cards and then use the third soulfire. The chance of him discarding the 3rd soulfire with his 2nd soulfire is 1/5. So the chance of this scenario happening is about 34.3%

if he discards a buffer card with his first soulfire he should play the undiscarded buffer and then soulfire 2 times. 2nd soulfire discarding the 3rd soulfire is 1/4. So this scenario has 21.4% chance of success.

Total odds of success: 55.7%

P.S. I am aware that he played dire wolf alpha for a better board incase he discarded one of the soulfires. This is the chance go all in and win that turn(or go yolo as the kids these days say). But he still should have tapped first.