Long story short, split with ex in 2014, his contact with DS (now 7) has been sporadic at best, even though he lives 20 min walk away. I think this year ex has seen DS 8 times (for approx an hour each time) and did video call him every few weeks, but that's dropped off now.
DS rarely mentions him and even then it's just in passing (that's where my daddy lives), when he does, I tentatively ask would he like to see him, and he always just answers "Maybe"
I'm in 2 minds about whether to contact ex to suggest seeing him before Christmas. I stopped pushing for contact after about a year of me suggesting times and days to meet up. bringing DS to him and then sometimes him cancelling. It was always me suggesting it. I don't know what he'd bring to DS's life if he did see him for Christmas.