I used cytotec (misoprostol) to abort but didn't bleed. U/s showed 5 weeks and 6 days fetus but no heartbeat. Will 7 weeks fetus on next ultrasound have heartbeat?

Time will tell. No way to predict. If your dates were consistent with a 5wk6d pregnancy chances are pretty good. If the fetus is alive then there should be definite fetal heart activity visible at 7 weeks especially with a vaginal scan. Hope things work out the way you want.