The road between Bridge of Gairn and Gairnsheil may be closed to traffic. They are going to build a new bridge at Gairnshiel. https://online.aberdeenshire.gov.uk/Apps/roadworks/pdf/11.4.22A939%20Gairnsheil%20Closure%20map.pdf

https://moxonarchitects.com/projects/562-gairnsheil

I would be surprised if the foot bridge wasn't still there, it was late last summer and we haven't had any serious flooding storms over the winter, wind storms yes but not the type of weather that knocks out bridges. There is also a very shallow ford near the bridge that unless the river is very high can be easily crossed on foot.

As Louise says it is possible to stay on the North Eastern side of the Gairn and join the more minor road near Lary, I would stay on the northern track at Dalfad and take the pleasant route through the woods, much nicer than road walking along the A939.