Does a thief pay seven-fold?
Rashi (32) #1: Seven is not precise; it refers to many payment of Kefel, even 50 on one principal 1
Rashi (32) #2: Yes - if he stole an ox and its Kelim, and slaughtered it, he pays five times for the ox, and double for the Kelim.
Rashi (35): This refers to one who covertly goes to learn. In the end he will be appointed a judge and give rulings. "Shiv'asayim" refers to Torah - "Mezukak Shiv'asayim" (Tehilim 12:7).
Malbim: If he stole [and later slaughtered or sold] an ox, he pays four times in addition to returning the ox; for a Seh, he pays an extra three.
If he stole it repeatedly. (PF)
Does a thief pay all his wealth?
Rashi: He might need to sell everything that he owns. However, there is a solution via payment.