It's important not to confuse the amount of heat the Earth has radiated in its lifetime (a quantity you have no access to here) with its current heat content. This question is asking you to neglect all the heat radiated (which could be affected by things like radioactivity), and just look at the current heat content, and ask if that is much more, or much less, than the gravitational energy GM^2/R. So find some way to get the interior T of the Earth (not the surface T, that has nothing to do with this question), and you should find that the total heat content is way less than the gravitational energy released.
The virial theorem was mentioned above, so if you know about that, you might have thought the heat content would be half the gravitational energy. That's only true of normal stars, which are held up by the gas pressure of largely noninteracting particles, whereas the Earth is held up by forces within the rocks that are not included in the usual virial theorem and have little to do with heat content.
Still, the gravitational energy gives the energy that was released in forming the Earth, so when you find how little the heat content is in comparison, it gives you a good idea of how much the Earth has cooled since forming. It also gives you a lower bound on how much net heat it has radiated (over and above the heat of sunlight it has absorbed). It's only a lower bound because there are also internal radioactive heat sources, but I believe their sum total effect is still fairly small compared to GM^2/R.
Hence the answer to your question is going to turn out to be "yes" when you do that comparison. (I wouldn't give that spoiler except that some of the answers above might have led you to think the answer should be "no.")