First of all, I'd certainly play Luis Gustavo over Gagliardini today if I had both of them in my team so as far as improving short term goes, that's easily the better choice. Difficult to argue about that when we simply compare the resumés...
Secondly, it's hard to see us close a deal for 7 mil less than someone else is offering. And being sure about it, is certainly not realistic.
Last but not least, Gagliardini looks like a talent to me, one bigger than Kessié but it is still a gamble and we do not know who we'll target/buy this summer. There's no need to buy another talent if we're to add a midfielder or 2 with starting quality. That would bench and ruin your talent unless you loan him... which makes splashing all that cash all the more stupid. Especially since we already own players like Sensi, Mandragora, etc. or at least have options on them.