How many spies that were sent to Canaan were willing to believe God's promise?

Answer 1

Two. They were Caleb and Joshua (Numbers ch.13-14).

See also:

The incident of the spies and other complaints in the wilderness

Answer 2

The Book of Numbers contains two distinct spies stories. Rather than choose between them, the Redactor interwove the two stories so that to a casual reader they seem like one, rather complex story. In one story, only Caleb believed; in the second story, Caleb and Joshua believed in God's promise. The details follow:

In the first version: Moses dispatched the spies (13:17b-20); the spies travelled only as far north as Hebron (in the future kingdom of Judah) (13:22-25); the spies returned and issued their report to one person (Moses), stating that the land was ‘flowing with milk and honey’, but that the inhabitants were giants and their cities fortified (13:27-29); Caleb alone tried to encourage the Israelites to proceed with the conquest (13:30); the spies countered Caleb's claim, stating that the land was unconquerable (13:31,33); the people refused to enter Canaan and plotted to elect a new captain to lead them back to Egypt (14:1b, 4);God was angry, threatening to destroy the people by plague (14:11-12);God chose not to destroy the Israelites, instead they were to wander the desert until the present generation had died, and Caleb alone of this generation would live to enter the Promised Land (14:20-25).

In the second version: Moses appointed twelve heads of tribes to scout the land, and dispatched them from the Wilderness of Paran (13:1-17a); the spies toured the entire Promised Land, “from the Wilderness of Zin to the entrance to Hamath (southern Syria)” (13:21); the spies returned and displayed the land's fruit, issuing their report to Moses, Aaron and all the congregation (13:25-26); The report stated that Canaan was not only unconquerable, but a ‘land that devours its inhabitants’ (13:32-33);The Israelites refused to enter Canaan (14:1a, 2-3); Caleb and Joshua both tried to encourage the Israelites to proceed with the conquest, but the Israelites responded by calling for them to be stoned (14:6-10a);God was angry and decreed that the Israelites will wander the wilderness for forty years – one year for each day they had spent in scouting the land – until the present sinful generation had died, but Caleb and Joshua would live to enter the Promised Land (14: 26-35).

Answer 3

Out of the twelve spies sent to Canaan, only two—Joshua and Caleb—were willing to believe and trust in God's promise that He would give them the land. The others allowed fear, doubt, and lack of faith to cloud their judgment, leading to a negative report.