From the overall h2h, both teams have met 3 times and Milan was able to beat Inter 2 times and Inter was only able to draw 1 time. So I have an assumption that Milan has a higher spirit and ambition to qualify for the final round. Because Milan has no chance of winning the title in serie A and will certainly be more confident in the Coppa Italia.
The fact is that Inter Milan's first target is to secure the Serie A title. And the second target is to perform well in the Champions League. It is not certain whether Inter Milan will give their full effort for the Coppa Italia title. On the other hand, AC Milan is unlikely to win the Serie A title. The team will not even be able to reach the top four of the table. Now AC Milan will try their best to secure the Coppa Italia title.
The coach of Inter Milan will likely not use his full squad in the match because winning the Seria A and the champions League competition will be his major concentration right now since the games are not so far again so I think AC Milan has a higher chances of winning Inter Milan because they will take the game more serious as it stand as their only chance of winning a trophy this season based on their performance and position in the league. AC Milan's performance when they play Inter Milan is usually better that's one other reason why they stand a better chance of winning the game tonight though Inter Milan will still play well but I think AC should have more advantage to win the game.