Inter is indeed in better condition and the last 5 weeks in Serie A show them in a positive trend compared to Milan but remember this is a semi final match and we also have to consider the rivalry of the two teams besides that if we still remember Inter defeat in the Italian Super Cup final we have to consider that Milan could do it again.
Let's see the opportunities given by the bookies.

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 chances are quite high for both teams and even for BTTS the bookies give odds @1.80, I doubt whether both teams will be able to score.
I predict there are 2 possibilities, Milan win or draw. If Milan win, the score will end 1-0. But if it ends in a draw, the score will end 1-1. But I will take the risk betting on Milan win to get a big odds.