From Interlaken Ost train to Lauterbrunnen, train to Kleine Scheidegg, then train to Jungfraujoch. 2 h 50 min SFr 29.
No, there is no direct train from Interlaken to Jungfraujoch. However, there are services departing from Interlaken Ost and arriving at Jungfraujoch via Lauterbrunnen and Kleine Scheidegg. The journey, including transfers, takes approximately 2 h 50 min.