Yes. When the nights are below freezing and the days are above freezing, you may collect sap from the trees, even in the Fall. Some producers who have tried fall tapping have reported that the sugar content is lower and niter content is higher but you can still make syrup! Many studies on climate change show that the sugaring season is getting earlier and earlier as it is.
If you do tap in the autumn, you may want to avoid tapping in the Spring just to give your tree a break.