Yes it is true that Jesus was seen by over 500 people after he was born. Please Read John 20 for the explanation of this biblical truth. Because of the size of the chapter I have hyper-linked John 20 above to the appropriate part of scripture for reading.
The next area of biblical truth focuses on the writings of Paul to the church in Corinth. This area of scripture show Jesus was alive after the crucifixion and showed himself to more than 500 people to validate his divinity.
1 Now I make known to you, brethren, the gospel which I preached to you, which also you received, in which also you stand,
2 by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain.
3 For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures,
4 and that He was buried, and that He was raised on the third day according to the Scriptures,
5 and that He appeared to Cephas, then to the twelve.
6 After that He appeared to more than five hundred brethren at one time, most of whom remain until now, but some have fallen asleep;
7 then He appeared to James, then to all the apostles;
8 and last of all, as to one untimely born, He appeared to me also.
9 For I am the least of the apostles, and not fit to be called an apostle, because I persecuted the church of God.
1 Cor 15:1-9 (NASB)