No physical way that Doflamingo can beat Aokiji.
Doflamingo has busoshoku haki, meaning he can damage logias.
His wires/strings were shown in the previous chapter, when he fought G5.
Though busoshoku can touch logia's, as robin stated, it can't stop them from reforming, it can only damage the actual body through harming the devil fruit body, rather than moving through it.
On contact with aokiji, the wires/strings will turn into ice and freeze.
There is no way that Doflamingo can beat or touch aokiji, especially when he can survive haki attacks from someone able to deflect a mihawk slash (Jozu).