It seems necessary that you investigate your extraction process and find out why some segments are missed, instead of fixing it afterwards. The gap is quite significant and should not be resolved with a simple tolerance or snapping.
If you really have to fix the gap, you may need to:
1. use Feature Vertices To Points tool with DANGLE option to get all dangle endpoints.
2. use Buffer with a distance at least half of the maximum gap length to buffer the dangle points. Hopefully each pair of dangle points at a gap will be covered by a buffer polygon.
3. Intersect the dangle points with the buffers.
4. use Points To Line tool with the polygon ID as the Line ID Field to create lines for the gaps.
I wrote the above without testing.You may need additional steps to get it right.